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CHEMICAL NEWS,
July 21, 1876.

Notes on Blowpipe Analysis.

end of the arm which indicates the force on a dial; and in another instance by the air acting upon hollow cylindrical cups hung in the current, by which a finger is worked on a dial plate. He also describes various watergauges, both for ordinary and for great precision, including, amongst the latter, one having one of the limbs inclined.

These are apparently the principal anemometers which have as yet been introduced, either above or below ground. It is possible, however, that others may have been used, and even that some of them may have been invented by other persons than those whose names they now bear. Indeed, looking at the instruments generally, there is little more of any principle in them beyond what appears either in the windmill, or what may be exemplified by a light substance hung from a cord.

(To be continued.)

NOTES ON BLOWPIPE ANALYSIS.
By H. B. CORNWALL.

In a note published in the American Chemist, March, 1872,
I stated that Van Kobell's iodide of potassium and sul-
phur test for bismuth gave also a marked reaction with
lead compounds. The characteristic yellow sublimate
which it affords with lead compounds is nearly as volatile
as the real sublimate obtained by it with bismuth com-
pounds, both of them being formed at a greater distance
from the assay than the simple yellow coatings of oxides
of lead and bismuth which frequently accompany them.
The iodide of potassium and sulphur mixture constitutes
a simple and very delicate test for lead, even in presence
of a very large amount of bismuth, as experiments will
show, and I direct the students to rely chiefly upon it;
remembering only that the iodide of lead (?) sublimate is
much more volatile than the simple yellow coating of
oxide of bismuth or lead, which always lies near the
assay. A few precautions are necessary in using the
mixture as a test for lead, and also for bismuth to a cer-
tain extent.

Mercury compounds will often afford a yellow, sometimes a reddish sublimate with the mixture; sulphide of arsenic in large quantities, a yellow sublimate; sulphide of antimony, an orange, sometimes a reddish sublimate; cadmium compounds the yellowish brown coating of cadmium oxide, which might mislead beginners; all of these can be removed by a preliminary treatment with a moderate oxidising flame, to such an extent as not to interfere with the lead or bismuth reaction, and they should be so removed when present in large quantities. Finally, some tin compounds yield a yellowish sublimate with the iodide mixture, but it is very near the assay, and quickly becomes white on continuing the blast. These facts have partly been brought to my notice during practice with classes, and therefore will be of interest mainly to beginners, who are most liable to be deceived by the reactions given. The mixture is, however, highly to be recommended in testing for lead, having given indications of that metal in bronze and cadmiferous calamine, when all other blowpipe tests failed; the lead in the bronze was overlooked by an experienced chemist.-American Chemist.

University of Michigan.-We have received an account of the course of study pursued in the laboratory of analytical and applied chemistry in the University of Michigan also a list of the professors, among whom we find the well-known name of Dr. A. B. Prescott, a list of the works used as authorities, &c.

PROCEEDINGS OF SOCIETIES.

27

NEWCASTLE-UPON-TYNE CHEMICAL SOCIETY.
General Meeting, March 23rd, 1876.

JOHN PATTINSON, President, in the Chair.
DISCUSSION ON JONES AND WALSH'S DECOMPOSING
FURNACE.

(Concluded from p. 268.)

MR. H. L. PATTINSON said he had visited the works of
Messrs. Jones and Co., and he had seen the first pan, and
more recently the larger pan, in operation and he could
certainly bear testimony to the fact of there being no gas
escape. Of course he could not say anything as to the
He was very much
quantity of the gas condensed.
satisfied with the admirable way in which the material
seemed to be wrought. He never saw a more beautiful
sulphate in his life. There was not a lump in it larger
than the size of a hazel nut, and even these lumps when
broken showed a perfect decomposition. He thought that
if Mr. Jones would give them some of the tests of the
sulphate they would be interesting. Those which he got
when he was there were very good indeed. If he charged
his memory rightly there was something like I per cent
of free acid, showing probably that there was not a very
high temperature, and there was a very small quantity of
chloride-three-tenths per cent-showing that the decom-
position was very perfect. He thought it would be well
to supplement some of Mr. Jones's remarks also on that
point; if by any accident an insufficient quantity of acid
had been added to the salt, they could correct that by
adding a little acid during the process and before the
charge was withdrawn. It was only necessary to sprinkle
in the additional estimated quantity of acid. That was
very rapidly disseminated through the mass, and thus
succeeded in bringing it to a perfect decomposition. On
the other hand, if there was an excess of acid, it was only
necessary to put in a little salt; that also was rapidly
mixed by the action of the machine and took up any
excess of free acid. He thought that the output, even of
the furnace which Messrs. Jones now had at work, could
be very largely increased by a better draught. He thought
Messrs. Jones would probably agree with him that the
deficient draught was probably owing to their having,
from the nature of the place, been obliged to take the flue
below the floor. It suddenly dropped from the roof of the
furnace under ground, then rose again after a considerable
distance, and as they all knew that a pulldown draught
was disadvantageous, they would probably with a better
arrangement of the draught get a better result. The first
furnace, he thought, was working much more satisfac-
torily, and, for its size, turning out a larger quantity of
sulphate. The draught was, at all events, sufficient, even
in the large furnace, to do away with any nuisance such
as we have even in our well-draughted open condensing
furnaces. There was no nuisance when the charge was
drawn, and they all as practical manufacturers, knew
what a nuisance it was having the batches imperfectly
wrought. There was no gas that he could complain of,
and he thoug t nobody could. There was a little pungent
odour, but nothing to be a nuisance. He was very much
pleased with the whole thing, and thought that when
little improvements were made in the way of charging, by
a hopper on the top of the furnace probably, and also by
the alteration of the gear, so as to draw the charge out
through a slide in the furnace bottom, a great deal of time
would be saved, and he should think that probably
instead of their getting three batches out in the twenty-
four hours, there would be no difficulty in getting out
four. He would be very much disappointed if, in the
furnace his firm had now ordered and were proceeding to
erect, they did not get out 100 tons per week.

Mr. NEWALL said he went over to Middlesbrough and

28

Newcastle-upon-Tyne Chemical Society.

saw the furnace at work and was very much pleased with it, and thought it did the work very well. Of course they all knew they were very much at the mercy of workmen now-a-days; and at Washington they had had the same cause of complaint which they had had at Middlesbrough. He regretted that Mr. Clapham had not informed them what steps had been taken previously in the same direction. If the records of the Patent Office were examined it would be found that some twenty-seven years ago Mr. William Pattinson, of the Felling, took out a patent for apparatus almost identical with that patented by Mr. Jones. The difference was very slight; and if Mr. Pattinson's plan was examined it would be found that it had been apparently much more well considered than the specification of Mr. Jones. The drawings attached to Mr. Pattinson's specifications were working drawings; in the other they were rather the reverse; but Mr. Pattinson showed clearly that his plan could be carried out for these furnaces. He had proposed two pans, and of course would do double the work in the same time that was done in one, or very nearly so; but the two processes appeared to him so identical that he could not conceive a patent taken out for this process now. The whole of the mechanical arrangement for the operation in Mr. Pattinson's plan was complete. He had gear which drove the stirrer at a certain speed during the process of decomposition, and when that was completed he reversed the mechanism by a clutch and drove the stirrers again at four times the speed, so as to expel the sulphate at the end of the operation four times as quickly as it was stirred up before. He thought it was worth looking at as a better contrivance than the one before them; but otherwise the two plans appeared to him to be identical.

Mr. H. L. PATTINSON said he imagined that the essence of Mr. Jones's plan in opposition to his cousin, Mr. William Pattinson's patent was this-that the whole operation was completed in one pan and furnace.

Mr. GLOVER said that as Mr. Newall had mentioned the patent of Mr. Wm. Pattinson he might say that he happened to be at the Felling at the very time the plan was brought out and worked. He was there until it was discontinued, and he tested the products during the whole of the time. Unfortunately Mr. Wm. Pattinson did not carry out his process to the successful issue which Mr. Jones had done, and he thought that Mr. Wm. Pattinson would be the first to admit that that constituted a very strong claim to the patronage and sympathy of the trade. He recollected that at that time Mr. W. Pattinson's main object was to work balls. He worked the furnace for many months as a ball furnace. His great d fficulty at that time was not so much keeping up the motion and working the material well, as to get a material for the tools which would stand the corrosive action of the sulphides. As Mr. Newall said, the machinery which was contrived and executed was almost perfect-the action of it was perfect. Mr. Pattinson saw it was necessary in applying it to a ball furnace, where the temperature was so high, to have a cooling apparatus, and he believed Mr. Pattinson specified water, though he used air. But he should think that at least twenty-five years had elapsed since the experiment was abandoned, and he thought that both morally, and even legally, Mr. Jones's patent deserved their support, and he believed that legally it would obtain it.

Mr. JONES said he was very glad Mr. Newall had named this matter, because it gave him an opportunity of explanation. His friend Mr. Hugh Lee Pattinson was himself over at their works amongst the first to see the furnace in operation, and at the time he told him of the furnace which had been designed by his relative, and also the use to which it had been applied; and he gathered from Mr. Pattinson's remarks at that time, that the main, if not the sole, use of this furnace was for carbonating.

Mr. GLOYER-We tried it for carbonating, but chiefly for balls.

{CHEMICAL NEWS,

July 21, 1875.

Mr. JONES added that the machinery of it was described to him, but it was not till his return home from Sicily a few days ago that he was aware the furnace had been patented. The main principle of their patent was simply what had been described by Mr. Pattinson-that they did the whole of the operation at one time. They commenced and finished the operation, as it were, at one charge, and thus saved the labour of the twofold operation of having first to decompose the salt in one vessel, and then afterwards transfer it into another vessel to be finished, which, to his mind, would render the furnace of Mr. Pattinson, even supposing it had been applied to decomposing, so costly to work as to very largely, if not entirely, nullify the benefits to be obtained in their patent by cheapening labour.

Dr. LUNGE said he had not seen the patent of Mr. Wm. Pattinson, but he was informed that Mr. Pattinson distinctly disclaimed the use of revolving machinery in the acid pans, and that constituted a very important differOf course, by that plan the breakage of the pans would be very much what it is at present.

ence.

Mr. MOND said he gathered, from what the several speakers had said, that the work in this furnace must be essentially different to the ordinary pan. Both Mr. Clapham and Mr. Jones remarked the evolution of the gas was constant, and he also gathered from Dr. Lunge, in conversation, that the mass never got into a solid state. If that were so, he should wish it to be explained; because, in that case, it was not only a new furnace, but an entirely new process in making sulphate, and appeared to him to be a very important innovation. Might he ask Mr. Jones to explain if he was right in this supposition?

The PRESIDENT thought that at one time, in the beginning of Mr. Jones's experiment, the mass was fluid at the commencement of the batch.

Mr. JONES-Not very fluid. The sait took the acid quickly.

The PRESIDENT-You added the salt very quickly?
Mr. JONES--Yes.

Mr. GLOVER-Have you ascertained accurately the percentage of sulphuric acid you used on the salt?

He

Mr. JONES said that Mr. Dyson, manager for Messrs. Muspratt, Bros., and Huntley, was over at their works last week, and took charge of the furnace while he was there. He was allowed to do what he liked with it. weighed one charge of the materials taken, and the results were as follows:-Common salt, 3 tons 10 cwts.; sulphuric acid of 140°, equal to 2 tons 17 cwts. 3 qrs. of 170°. Mr. CLAPHAM-What percentage?

Mr. JONES said he had not worked it out, neither had Mr. Dyson, but it was 140° acid, equal to 2 tons 17 cwts. 3 qrs.

Mr. GLOVER-Of oil of vitriol?

Mr. JONES-Yes. The finished sulphate which he got out he weighed at 3 tons, 15 cwts., and estimated that he had left cwts. of sulphate of soda in the furnace, making the total weight of sulphate of soda produced 4 tons. He could not get it all out; it was drawn out by a hand rake.

Mr. HILL said by that Mr. Jones would make out that he had used 82.5 per cent of acid of 170°, and got 114 per cent of sulphate upon the salt charged.

Mr. JONES said he had not worked it out. Mr. HILL said this was what the figures which Mr. Jones had given brought out. There was just a doubt about the 114 per cent of sulphate on the salt charged, because the general experience on the Tyne led to a very much lower result, unless the salt was very dry.

Mr. JONES-The sulphate obtained was 4 tons. Mr. HILL-Do you know the moisture in the salt? Mr. JONES-No; but I think it was dry salt. You could not tell accurately from one batch.

Mr. HILL-That would account for a high percentage of sulphate.

Mr. JONES-There are no fluxings in this process. There is no possibility of any loss. I have not worked it

CHEMICAL NEWS,}

July 21, 1876.

Newcastle-upon-Tyne Chemical Society.

out in percentages. These are Mr. Dyson's results of his own work. He was allowed to have charge of the furnace for three days and two nights to do what he liked.

The PRESIDENT said the question which Mr. Mond wanted answered was this:-In what condition the salt and sulphuric acid were mixed together? Was all the salt put in at first, and a small quantity of acid added from time to time till all had been added? Or were the salt and acid put in in small quantities?

Mr. WALSH-We put in two tons of salt first to cover the pan bottom, and then turn on the acid tap, running the acid in in about twenty minutes, and then throw in the remainder of the salt.

The PRESIDENT-Is the whole of the acid put in at once ?

Mr. WALSH-Yes; it takes twenty minutes to run in, in 5 ton charges, and while the acid is running, the rest of the salt is put in.

Mr. GLOVER-The batch is never fluid?

Mr. WALSH-Well, it is in what you may call a thick pulp. It never becomes thin as in the ordinary decomposing pan. It is pasty and stiff.

Dr. LUNGE said he noticed specially the point which Mr. Mond had raised. It never became fluid, and there was not the slightest tendency to boil over. He asked if they used any tallow, and they said no.

Mr. CLAPHAM, in reply to Mr. Mond, said the sulphuric acid was very strong, and there would not on that account be such a liquid mass in the furnace as if it was a very weak acid. The batches he saw worked were not what he would call fluid. They were sufficiently pasty-he thought that was the correct term to use-for the knives to go through.

Mr. GOODMAN thought he would not offer any observations as to theory, because what he could say was simply as to practice. He would much rather say something about the machine after trial. He thought a great deal of credit was due to Messrs. Walsh and Jones for the way in which they had worked out this furnace. He thought a great deal of time was lost between the filling in of the salt and the withdrawing of the charge. That was of course merely a mechanical operation which would probably require a little time to work out. He believed that the charge had taken five and a half hours to work, and if it took from eight to nine, he could see that it must be either from the laxity of the draught or the long time it took to feed the salt in and get it out, because it sometimes sticks a little to the bottom. But these were matters of detail, and he had no doubt that an hour and a half, or something like that, ought to be saved on each batch in twenty-four hours, so that practically he had no doubt they could turn out 20 to 25 per cent more sulphate with a more carefully considered arrangement. There had been an objection raised to the bottom door, but he believed that the principal objection to the arrangement was that it was a sliding one, and that if the door stuck they could not get at it. There was no objection to the drop door, it was simply the sliding door; and there had been a doubt expressed by some parties as to whether a bottom door could be made tight. He believed Mr. Walsh's practice went to show it could be easily made tight, and that there was not any doubt as to the tightness of the bottom door in his case; but as he said the simple difficulty was to get the slide out if it was stuck in the bottom. But these were all mechanical arrangemen:s which he would rather not linger upon at present. At a future period they would no doubt have the opportunity of seeing the revised furnace for which he had drawn out the working plans. In a very short time one or two manufacturers would have them in work on the Tyne, and he was quite confident that the eighty tons which he thought Mr. Clapham spoke about in his paper could, first of all, be increased if the pan was about one-fifth more capacity than that of the pan which they were at present working. From one-fifth on eighty they would see what the result was, and by gaining about three or four hours out of the

29

twenty-four they would have a further gain on the whole result. So that dealing simply with practical matters, he believed they would be able easily to get up to 100 or 120 tons. Of course there would be improvements made from time to time in this furnace. Some people still considered that over-head gear in matters of this kind was better than under gear. These were inatters which only time could work out, at present what would suit one person's practice would not suit another's. For instance, when you brought the salt overhead it was more convenient to have under gear; under other circumstances it would be more convenient to have overhead gear. But these were mere matters of detail, and he thought they would be able to arrive at satisfactory conclusions if they satisfied their minds on the chemical portion of the work.

Mr. PATTINSON, with respect to the wear and tear of the furnace, said, of course he had no experience, and probably no one had any experience, because it had not been in operation long. It was a most vital point, and time only could clear it up. Perhaps Mr. Jones would give them any results they had arrived at.

Mr. JONES said there was not much to be said upon that point. But the first furnace they put up was put up with a very slight pan; he thought the metal would not be more than 1 inches thick. That pan was soon cracked, for the reason that all the work had been very home-made, and the pan put up too close to the fire; it was simply cracked by the heat of the fire, for being set upon pillars the radiation of heat caused unequal expansion. But, in the pan which he had described, which had been in regular work since last November, there was no appreciable wear and tear to this day. It had been carefully examined and measured in every part. There was an air-way between the edge of the pan and the fire, and therefore the fire had no direct effect upon it; and gentlemen would see that when there was no bottom heat going under the pan, and heat passing over a considerable distance above the surface of the pan, there was really very little risk of its breaking. He did not know what might be the life of a pan; it would be mere speculation to give a guess at it. But there was no visible wear and tear in the pan at this day, which was begun last Noven.ber. With regard to the internal machinery, he had already stated, that while it was of wrought-iron there was a tendency in it to bend, especially when the charge became of a thick pasty state. The wrought-iron then having a considerable strain upon it, the arms were apt to bend a little out of shape. That, however, had not been observed since the wrought-iron arms had been replaced by metal arms, and that was the reason why the original furnace had been stopped, in order to have those wrought-iron arms taken out and metal arms put into it. There was no difficulty whatever in working it with metal arms of sufficient strength, and with metal scrapers and ploughs; and the wear was reduced practically to that upon the scrapers, and which was really very little. They only kept one smith at that class of work in their own works, and he really had nothing to do at this machine now. The smith used to be kept going constantly repairing the tools for the old decomposing pot.

The PRESIDENT said the matter had been pretty fully discussed, but one point had not been made very clear to his mind, and he thought it would be very advisable to have information upon it, which would perhaps be forthcoming at the next meeting-that was, as to the exact quantity of hydrochloric acid which was produced. Not only did they want to know the kind of condensation which had taken place, but they wanted to know how much muriatic acid had been obtained from a certain quantity of salt decomposed. That had not been very clearly stated by Mr. Jones, and probably, as he said, they had no data to make the calculation. But he hoped that at the next meeting Mr. Jones would be prepared to state how much hydrochloric acid was obtained from a certain amount of salt. Whether Henderson's process was likely to supersede all the others, and sweep the present plant

30

Analysis of Manganese Ore.

off the face of the earth they could not tell; but it was quite clear, he thought, that Messrs, Jones's furnace was a very great improvement on our present decomposing plant, and they ought to be very much obliged to those gentlemen for bringing before them such an important discovery. There was evidently a very material saving of labour and labour of a disagreeable kind, which was a very important consideration in these times. He had great pleasure in moving that a vote of thanks be given to Mr. Clapham for his paper, and to Mr. Jones and Mr. Walsh for attending there to give them the explanation of the working of their furnace.

CORRESPONDENCE.

ANALYSIS OF MANGANESE ORE.

To the Editor of the Chemical News. SIR,-From his letter (CHEMICAL News, vol. xxxiv., p. 19), I fear Dr. Phipson has not understood my query on the determination of the oxides of manganese, and I must therefore request the opportunity of explaining myself further. As Dr. Phipson is no novice I erroneously imagined that he would at once appreciate my meaning. In the CHEMICAL NEWS (vol. xxxiii., p. 243) Dr. Phipson published in your columns a very elaborate analysis of a sample of manganese ore, which your contributor had found to contain 72'17 per cent of MnO2. There was an additional quantity of manganese beyond the amount present in the above form, and this Dr. Phipson assumed to exist as Mn2O3, 6'20 per cent being thus accounted for. In my last letter, I, in effect, asked if Dr. Phipson had any means of distinguishing this Mn2O3 from a mixture or combination in atomic proportions of MnO and MnO2 (=Mn2O3), and I receive the unsatisfactory answer that Dr. Phipson "discovered the manganic oxide (Mn2O3) in a very simple manner, namely, by determining in the first place the total quantity of oxygen, and in the next the total quantity of manganese. These two data are quite sufficient for the purpose."

As well might Dr. Phipson attempt to distinguish acetate of ethyl from butyric acid (both of which have the same empirical formula) by determination of the carbon and hydrogen as think he can tell Mn2O3 from MnO+MnO2 by merely ascertaining the proportion of manganese and oxygen, for a glance will show that the percentage composition is the same in each case.

Unfortunately, as a provincial chemist, the French edition of H. Rose's chemistry is not readily accessible, but I think the author would scarcely thank Dr. Phipson for fathering such a method on him.

My question was asked in perfect good faith, as I really thought there might be some means of arriving at the information sought. As it is I will ask your correspondent a few other questions, and challenge him to reply.

1. How does Dr. Phipson know that the 6:20 per cent of Mn2O3 which appears in his analysis was not made up of 3'41 of MnO2 and 2.79 of MnO ?

2. If he does not know, how did he distinguish the 3'41 per cent of MnO2 from the 72'17 admitted to be present? 3. What process was employed for the determination of the main quantity of MnO2, and would not the amount found include the 3'41 per cent, assuming the latter to have any existence?

4. If the result of the determination of the MnO2 (=7217) represents the total quantity of that oxide present, must not the remainder of the manganese necessarily have existed as MnO and not as MnO+MnO2 (= Mn2O3)? 5. If the last question is answered in the affirmative, has not Dr. Phipson counted his oxygen twice over?I am, &c.,

Sheffield, July 15, 1876.

ALFRED H. ALLEN.

CHEMICAL NEWS,
July 21, 1876.

DR. J. W. Hearder, f.c.S.

To the Editor of the Chemical News. SIR,-Mr. Mendola, in his attack on Dr. Hearder, has, I think, entirely mistaken his grounds. The letters F.C.S., F.R.S., or F. any other S., show and mean nothing whatever except that the holder is supposed to have some interest in the work of the said S., and that he is held in sufficient estimation by the members to be permitted to join them. I have not the smallest doubt that this is fully and perfectly understood in its proper sense by every person of very ordinary intelligence. What little position such a qualification as this gives is undoubtedly made use of one way or another by almost every member of every Society in existence. It may not be that every one sends it out by thousands, but even the leaders of the Chemical Society are not free from this fault, if it is a fault. To print it on the title-page of a book, or in fact anywhere else (except in matters strictly connected with the Society), is not appreciably different to printing it on a circular. It would appear that Mr. Mendola has an exalted idea of the possible value of the Fellowship of the Chemical Society. If a brass farthing is polished, and held at a respectful distance from the eyes of the public, perhaps some may mistake it for a sovereign; but I think to attempt to persuade the educated classes that the Fellowship of a Society is any qualification is an insult to their common sense neither Dr. Hearder nor Mr. Griffin would be guilty of. I am not aware that the Fellows of the Royal or any other Society attempt to hide their light under a bushel if it can be exhibited to their own moral or pecuniary advantage, and the same remark applies to the whole class of what may be called the Societies of Specialists. Men of business, of which a large proportion of the Chemical Society is composed, do their advertising in their own way; those who are not men of business simply do it in another way amongst their friends and acquaintances, and make, or think they make, a moral profit instead of a pecuniary one. When a Fellow of any Society makes it known that he is one, as a matter of business, he simply takes an indirect means of giving references to his personal friends who have signed his application,-i.e., the fact of his being a member is, to a very limited extent, a moral guarantee that he is not absolutely unknown. If the Chemical Society transforms itself into a strictly professional Club, and goes out of business in the printing and publishing line except for its own members, then the use of the letters F.C.S. by the holder, except in matters strictly connected with the Society, might be considered improper.

It is an open question whether those who are raising the cry of discontent are not a few who-not being eligible or qualified for admission to the Royal Societywish to polish their farthing up to the utmost limits, and try to make it look like the real thing. To my mind the only way to do this will be to admit all as Associates at first, and afterwards make the Fellowship conditional on the contribution of original papers or work to the Society. This revolution might include the whole of the existing Fellows who had not contributed any original work since their election. The rule might be that Associates should be elected as Fellows on the publication of any Paper of theirs in the Transactions after it had been accepted and read at one of the meetings. This would give the Fellows a slightly better position than they now hold, and would no doubt considerably increase the amount of original work published, more especially if all Fellows after their election were liable to be called on for Papers at intervals of say not less than one year. This would do what neither blackballing nor raising fees could do, and would be practically equivalent to an examination without its weak points. The position of the Society can be improved better without the use of personalities, and if the discussion of the matter is left entirely to the Council it will be better for all parties concerned. When discontented members descend to personal attacks in public journals,

CHEMICAL NEWS,
July 21, 1876.

Chemical Notices from Foreign Sources.

31

the Society must be getting in a bad way, and it is time, has been made. This theory, as we know, is subdivided for the Council to take the matter in hand. I am, &c.,

Warrington, July 18, 1876.

THOS. FLETCHER.

into various doctrines, of which a very complete and lucid exposition has been given by M. Bertin in the June number of the Annales de Chimie et de Physique. The capital objection which mechanicians oppose to these different explanations is, they are all reduced to admit, that the

CHEMICAL NOTICES FROM FOREIGN radiometer is an instrument of reaction. But in such

SOURCES.

apparatus, having regard to the impossibility of the motive power being rapidly produced with a sufficiently constant intensity, there ensue merely rotations accompanied by

NOTE.-All degrees of temperature are Centigrade, unless otherwise retardations and bounds far from being reconcilable with expressed.

the perfect regularity of the radiometer. Moreover, the theory in question expressly requires that there shall never be an equilibrium of temperature between the gas in the case and the discs of the radiometer. But how are we to admit that in every experiment this equilibrium is not ultimately established? Moreover, the rotation ought to stop at last instead of maintaining itself indefinitely at the same speed. The author then cites certain experiments difficult to explain by the supposed movement of gases in the interior of the apparatus. Thus the instrument was heated nearly to redness, when it commenced turning, but the rotation was sensibly accelerated by the momentary presence of a single flame, which joined its action to that of the radiant heat. An apparatus was constructed with discs exclusively polished. On throwing a pencil of solar rays upon one of the two hemispheres of the glass case a perfect rotation was obtained, without interruption, and as free and rapid as with an ordinary radiometer fully exposed to the light. The author bases his explanation of the phenomena upon a mechanical action of the "ether" perpendicular to the direction of its rays of propagation, and not in the same direction as these rays. This interpretation is calculated to calm the legitimate disquiet of the partisans of undulation. In Germany there is a leaning to an explanation based upon electricity. They rely upon the experiment that when a radiometer with discs exclusively polished, and where one of the hemispheres of the case is traversed by a continuous electric spark, the instrument akes a rapid rotation always opposite to the direction of the spark, this direction being understood according to the common convention. "In any case the radiometer of Mr. Crookes seems to us a serious instru

Comptes Rendus Hebdomadaires des Seances, de l'Acadenie des Sciences. No. 26, June 26, 1876. Maximum of the Possible Repulsive Power of the Solar Rays.-M. G. A. Hirn. The attention of the scientific world has been latterly drawn to the singular phenomena which Mr. Crookes has studied with the radiometer. The conclusion which has presented itself to the mind of many is that these phenomena are due to an impulsive action of the luminous rays, and that it is thus demonstrated that light is a movement of ponderable matter. Nevertheless, the phenomena discovered by Mr. Crookes have been elucidated, if not in their cause, still in their form and their starting-point. The ingenious counter-proof to which M. Arthur Schuster has submitted them places it beyond doubt that it is by no means the direct action of the rays emanating from the luminous source which determines the movement of the discs of the radiometer, but that the repulsive power here called into play has its seat in the walls of the transparent vessel which serves to contain the mill, and that this power is set in action by the pencil of rays directed upon the apparatus. As the true explanation of the totality of the phenomena has not yet been given, and as the hypothesis of the materiality and of the impulsive force of light will probably not soon be abandoned, the author thinks it useful to submit this hypothesis to the test of the method of successive elimination. Mr. Crookes has calculated the apparent repulsion exerted by the solar rays at 1 grm. per square metre. This pressure is more than one thousand times greater than the maximum value possible for reflecting bodies, and more than two thousand times superiorment, and not a paradoxical apparatus destined to enjoy to the maximum value possible for absorbing bodies. We may, then, affirm that the phenomena which Mr. Crookes has made known are nowise due to the effect of an impulsion of light, and do not imply the idea of mass of density as regards radiant light and heat. However carefully the vacuum in the vessel enclosing the radiometer or torsion balance may be made, there remain, nevertheless, quantities of gas or vapour relatively enormous. The maximum pressure which the solar radiation can exert upon I square metre of absorbing surface is o'0004157 grm.: let us suppose that the discs of the radiometer are 10 square centimetres, the maximum pressure upon them will be 0'000004157 grm., or a little more than 10th of 1 grm. The slightest agitation of the small quantity of gas remaining in the apparatus will produce upon the radiometer pressure comparable to this. However transparent may be the glass case of the radiometer, it still absorbs a part of the calorific or luminous rays; one of its surfaces is heated more rapidly than the other. This inequality of temperature necessarily determines electric polarity, or the manifestation of static electricity. The vacuum, it is said, is so perfect that the electric spark cannot traverse the apparatus. But electric attractions and repulsions traverse the vacuum. However feeble may be this cause of attraction and repulsion, it may nevertheless have a considerable value in comparison with our maximum of 0'000004157 grm.

New Experimental Considerations on the Radiometer of Mr. Crookes.-M. A. Ledieu.-The author's experiments become less and less favourable to the theory of the apparatus based upon the movements of gases and vapours remaining within the glass case after the vacuum

an ephemeral scientific repute and then to rank as a mere physical amusement. Its experimental study, pursued under all modifications and with an indefatigable perseverance, will certainly lead to important results as to the mechanical properties of the ether."

Process for the Manufacture of Soda from Seaweed by Endosmotic Lixiviation.-M. L. Herland.-The author gives the following reasons for the depressed state of the seaweed industry: the weed is collected indiscriminately without regard to its greater or less richness in iodides or other useful salts. The weed destined for incineration is dried on the shore in the open air, whence results a decomposition and a loss of salts from the spray of the sea, dew, rain, &c. The process of incineration itself is the main cause of the weakness of the product in iodine, as a certain quantity is volatilised, but it is chiefly to the siliceous sand mixed with the weed that the great loss is due. In fact, silica at high temperatures reacts upon the iodides, producing alkaline-earthy silicates, and eliminating a certain quantity of iodine. The author, therefore, proposes the following method:-The fresh weed is placed in baskets of iron-wire, moved by a turning crane, and steeped in a series of vats containing about 50 kilos. of good quicklime per cubic metre of water, and arranged in circular batteries. The weed passes in succession from vat to vat, and is exhausted of all its useful salts. The same series of successive immersions is pursued with fresh weed until the first vat marks 43° to 4'5° on the hydrometer (pèse-sels, probably a Baumé's glass adapted for saline solutions). During this operation a double exchange takes place between the weed and the lime-water, by means of endosmosis. The time of steeping

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