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NOTICES OF PATENTS.

157

proved composition for coating iron or wooden ships'
bottoms."-August 16, 1865.

GRANTS OF PROVISIONAL PROTECTION FOR soap."-August 18, 1865.

SIX MONTHS.
Communicated by Mr. VAUGHAN, PATENT AGENT, 54, Chancery
Lane, W.C.

2129.

2140. A. Watt, Putney, "Certain improvements in 2246. W. T. Read, Great St. Helens, London, "Improvements in apparatus for stopping bottles." "An improve2248. W. E. Newton, Chancery Lane, ment in the manufacture of paper pulp." A communication from J. B. Brown, Peckshill, New York, U.S.A.August 31, 1865.

Improvements in the 2252. T. Lomas, North Shields, " separation of sulphide of iron from coal and carbonaceous matter."-September 1, 1865.

2123. O. Laurence, Euston Road, "A new medicine for the cure of the diseases of the stomach (dyspepsy, cardialgy, indigestion) and the hæmorrhoids."-August 17, 1865. G. H. Smith, North Perrott, Somersetshire, "An 2266. C. Reichen, Lincoln's Inn Fields, "Improveimprovement in dyeing and preparing hemp and other fibres for the manufacture of yarns and fabrics."-Augustments in preparing charges for firearms and for blasting." -September 2, 1865. 18, 1865. J. B. Austin, Victoria Wharf, Blackfriars, "Im2150. provements in apparatus for stopping bottles."-August 19, 1865. 2163. J. G. Avery, Regent Street, "A new composition suitable for use as paint and protective coating."-A communication from W. Potter, Saratoga, U.S.A.-August 22, 1865.

2101.

J. G. Dale, Warrington, and R. S. Dale, Manchester, “An improved preparation for the prevention of forgery of bank cheques, bills, and other documents."Aug. 14, 1865.

2187. C. A. Watkins, Greek Street, Westminster, "Improvements in apparatus for supplying carbonic acid gas to casks and other vessels from which beer, wine, and other fermented liquors are drawn."

2191. J. Moule, Hackney-road, "An improvement in the treatment of tar and other substances suitable to be used in the manufacture of paint, and for other purposes." -Aug. 25, 1865.

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2194. J. A. Wanklyn, London, "Improvements in the manufacture of violet dye-stuffs.' 'Improvements in the 2195. J. Fordred, Blackheath, treatment of certain products obtained in the refining of petroleum and of other hydro carbon oils."-Aug. 26, 1865. 2206. H. A. Bonneville, Rue du Mont Thabor, Paris, "Improvements in dyeing and fixing colours in fibres, yarns, and fabrics." A communication from A. Jeannolle, Commune de Clichy la Garonne, France.-Aug. 28, 1865. 2216. A. Gurilt, Birmingham, "Improvements in condensing and utilising sulphurous smokes and vapours, and in apparatus to be used for that purpose."-Aug. 29, 1865. W. Crookes, F.R.S., Wine Office Court, Fleet Street, "Improvements in extracting and separating gold and silver from their ores or matrices, and in the treatment of mercury employed for such purposes."

2229.

2231. J. H. Johnson, Lincoln's Inn Fields, "Improvements in tanning and in the preparation of extracts to be A communication from E D. Coëz, Paris. used therein."

-Aug. 30, 1865.

INVENTION PROTECTED BY THE DEPOSIT OF A COMPLETE
SPECIFICATION.

2314. J. Cast hélaz and N. Basset, Rue St. Croix de la
Bretonnene, Paris, "Improvements in the manufacture of
oxalic acid."-Recorded Sept. 9, 1865.
NOTICES TO PROCEED.

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'Improvements 1793. J. M. Macrum, Knightsbridge, in the manufacture of iron."-A communication from J. Williams and J. Copley, Pennsylvania, U.S.A.—May 7, 1865.

2023. J. A. Leon, G. Tegsimond, and J. Kissack, Liverpool," Improvements in apparatus for filtering sugar and other liquid solutions."-August 4, 1865.

2095. H. Woodward, Cannon-street," Improvements in carburetting coal gas and manufacturing artificial gas, and August 12, 1865. in the machinery or apparatus employed therein.".

2203. H. A. Bonneville, Paris, "Improvements in the alcohols."-A communication from F. D. Savalle, Paris.construction of apparatus for distilling and rectifying August 28, 1865.

1266. J. Swindells, Wigan, Lancashire, "Improvements in the manufacture of coal gas."-May 6, 1865.

1278 J. C. C. Halkett, Cramond House, county Midlothian, N.B., "An improved composition for coating iron or other vessels, and for other similar purposes."-May 9, 1865.

2096. R. A. W. Westley, Camden Road, Camden Town, "A combination of improved method, apparatus, and receptacles for storing, preserving, transferring, and discharging certain fluids for sanitary and protective purposes.' A communication from H. Pinkus, Boulogne, France.-Aug. 14, 1865.

1405. J. H. Johnson, Lincoln's Inn Fields, "An improved apparatus for freezing, icing, and cooling liquids." A communication from H. N. Dullmaque, Paris.

1409. R. Muller, Dartford, A. T. Weld, Gravesend, and J. F. Powell, Albion Place, Hyde Park, "Improvements in the preparation of materials to be used as substitutes for animal charcoal."—May 22, 1865.

2247. W. E. Newton, Chancery Lane, "Improvements in obtaining spirits of turpentine, rosin, pitch, tar, pyroligneous acid, and other products from wood." A communication from A. H. Emery, New York, U.S.A.-ing Aug. 31, 1865.

2267. H. Ellis, Bangor, North Wales, "Improvements in the manufacture of compounds of silica, and in the production of silicated alkaline inks, colours, and dyes." -Sept. 2, 1865.

2289. T. Nicholson, Gateshead, county of Durham, "An improved process of, and apparatus for, making caustic liquor or caustic lees."-Sept. 6, 1865.

2064. C. West, Queen's Place, Kennington Road, "An apparatus for giving immediate warning of undue heat, whether occasioned by fire, spontaneous combustion, or any other causes; of leakage in ships, and of the sudden irruption of water, and of the accumulation of choke-damp in mines."-August 9, 1865.

2120. S. Parry, Leadenhall Street, A new and im

1507. W. Clark, Chancery Lane, "Improvements in the means of carburetting or treating aëriform fluids for lightand heating purposes, and in apparatus for the same." A communication from H. A. G. du Vergiers, Marquis de la Rochejaquelin, Paris.-June 1, 1865.

1694. F. G. David, Paris, "An improved composition for the manufacture of printers' rollers.”—June 24, 1865.

Metallic Capsules.-We call the attention of our readers to the announcement of a meeting to be held at 17, Bloomsbury Square, on October 5, to take into consideration the present position of chemists and druggists in reference to the sale of capsuled articles. Recent proceedings have rendered united action on the part of the trade absolutely necessary. The best course that could be adopted would be a continuation of that already recommended-viz., to refuse to retail all capsuled articles.

i

CORRESPONDENCE.

Continental Science.

dates, not exceeding twenty years of age, is awarded an
exhibition of 30l., to the second one of 20., and to the
third one of 15, all for two years; to the fourth candi-
date a prize of tol. in books or money, and to the fifth
and sixth prizes of 57. in books, philosophical instruments,
or money.
On page 139. col. 1, line 5 from bottom,
'twenty should be twenty-three.' Lastly, concerning
line 1, col. 1, of page 140, I must state that the division
into groups' was abolished by an order published about
last December, and the subjects are now numbered con-
secutively, and one gold, one silver, and two bronze medals
given in each subject."

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Dr. Hofmann's “ Introduction to Chemistry.”—

PARIS, Septen.ber 9. AN ingenious piece of parlour magic has lately been introduced by the conjuror Cleverman, who produces a snake, or what at a distance may pass for the coils of a snake, at will. Something like a pastille is placed on a plate, a light is applied, and in a moment the pastille swells up, and seems to uncurl itself, and something resembling a snake appears on the plate. The preparation made use of is sulphocyanide of mercury (mercurous sulphocyanide), The new "Introduction to Chemistry, Experimental and which, as your readers will know, swells up when heated, Theoretic," which was announced last spring as in preparaand gives a very bulky laminated mass. Some nitrate of tion by Dr. Hofmann will, we are informed, be issued in potash is mixed with the sulphocyanide, so that the heat a few days. We hear that Dr. Hofmann has again availed may be applied within the mass, and the snake-like ap-himself of the colloboration of Mr. F. O. Ward, and in pearance of the residue is caused by the form in which the this work we may look for a Scientific pendant to the mixture is made up. Since vapour of mercury is given off admirable treatise on Applied Chemistry published by the in the combustion, it will not be advisable to repeat this same authors as the "Report on Class II., Section A., of experiment many times in one evening in a small room. the International Exhibition." The lectures Dr. HofStill less is it advisable to swallow one of the pastilles, as mann delivered last spring at the Royal Institution conI read in Les Mondes a certain Prince O- did, and so stitute the framework of the book, which, in its expanded form, will present a full exposition of the new system of notation, and the modern doctrines of atomic and molecular construction. The subject is confessedly one full of obscurity, and to many the new doctrines are quite a sealed book. It is, therefore, a matter of congratulation that a profound chemist like Dr. Hofmann, and a luminous writer like Mr. F. O. Ward, have been engaged conjointly in the elucidation of the difficulties. We look forward to the publication of this treatise with great interest. By the kind permission of Dr. Hofmann, we shall shortly be enabled to give our readers a chapter or two of the contents, illustrated with the original woodcuts.

nearly killed himself. The dose did not prove fatal to the Prince; but it did to a tapeworm he had the misfortune

to have associated with him. It must not be inferred from

this either that sulphocyanide of mercury is a safe remedy for tapeworm. It is really a most virulent poison, and if these toys come to be sold in England, the purchasers should be particularly cautioned not to leave them in the way of children. As made up here, they are not unlike lumps of pâte de guimauve, and the silly young Prince O began to eat one, mistaking it for a bonbon!

American Manufacture of Soda from Cryolite.

To the Editor of the CHEMICAL NEWS.

SIR,-Allow me to trespass on the space of your valuable
paper by making a remark concerning a letter in your last
number. A correspondent from Philadelphia mentions
the manufacture of soda from cryolite, and thinks the
importation of soda ash and caustic soda from England
into North America would be at an end if cryolite could
be obtained in sufficient quantity.
Now, I can state, on most reliable authority (my
informant is one of those German manufacturers who
have a contract for part of the cryolite, and could not
have any imaginable motive for imposing on me), that the
entire annual yield of the cryolite mines in Greenland is
10,000 tons, and that it is impossible at present to work
them for more than that. Half of this quantity, or 5000
tons, are contracted for by an American firm, and the
other half by various (three or four) manufacturers in
Denmark and Germany. Now, if you take in account

the fact that the whole of those 10,000 tons would not cover

by far the demand of a single of the large firms on the
Tyne or in Lancashire, it will be apparent enough that
there is no foundation whatever for the apprehensions of
your correspondent.
I am, &c.

South Shields, September 26.

GEO. LUNGE, Ph.D.

MISCELLANEOUS.

Prizes and Honours at the London University. -An esteemed correspondent sends us the following corrections of the statements in our last respecting the prizes at the London University :-" If you examine the calendar you will find that in January last the special honours examinations were abolished, and the candidates placed in the honours division ranked according to their proficiency n the subjects collectively. To the first of such candi

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Preparation of Oxygen.—Mr. R. W. Artleet, writing to the British Journal of Photography, says:— Having experimented on the valuable process for obtain. ing oxygen by the action of peroxide of cobalt on solution of hypochlorite of lime, with the view, among other things, of ascertaining what other substances might be possessed of the curious powers of the peroxide of cobalt, I have found that moist peroxide of iron or oxide of copper will answer the purpose. These substances, in the repeated trials I have made, have caused the evolution of a volume of oxygen equal to that obtained by means of the oxide of cobalt, and, like it, they lose none of their efficiency by The only difference I have observed is that, perhaps, the oxide of iron requires rather the highest heat to cause an equally rapid disengagement of gas. The oxide of copper answers perfectly, and if the oxide be not at hand, a few drops of nitrate of copper may be added to the hypochlorite of lime solution, and the gas will be given off abundantly immediately on the application of heat. I have also tried peroxide of manganese, but have not yet sufficiently investigated its action. I may, however, state that it does not accomplish the end in view so well as the other substances. The quantity of oxygen liberated is smaller, and permanganic acid is formed.'

use.

ANSWERS TO CORRESPONDENTS.

J. B.-Had better consult a medical man.

99 is thanked. For the two errors, not corrected, though evident enough, we hardly consider ourselves responsible. One is in the original French; the other in a copy furnished by the speaker.

Formation of Acetylene.-In answer to a correspondent, inquiring for the details of Dr. Odling's experiments, the Doctor writes as follows:-"I gave an account of my experiments on the formation of acetylene at the Cambridge meeting of the British Association There is a very short note on the subject in the report of that meeting; the reaction was also mentioned in Sir Wm. Armstrong's introductory addres at the Newcastle meeting, and in the appendix to the first the details of the experiments, having intended first to work up the volume of Watt's Dictionary of Chemistry.' I have never published matter more completely."

NEWS

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The Action of Aldehydes on Rosaniline,"
by M. HUGO SCHIFF.

I HAVE in former notes described the products of the action of aldehydes on some monamines (amylamine, aniline, toluidine) and on toluylenic diamine. We now purpose giving the results of our researches on the action of aldehydes on a triamine-rosaniline.

The action of aldehydes on aniline red was ascertained in 1865 by M. Lauth, who in this way obtained violet and blue matters. M. Lauth supposes that aldehydes act on aniline red as reducing agents; but this is not the case, they act on rosaniline as on other amines; the water is eliminated, and typical hydrogen substituted by the diatomic residues of the aldehydes. Salts of rosaniline may be operated on directly. Onanthic aldehyde acts at the ordinary temperature. By pouring the aldehyde on crystallised acetate of rosaniline, the crystals lose form and lustre and absorb the liquid. Fresh quantities of the aldehyde should be added, while triturating the mixture in a capsule, so long as absorption takes place. A crystalline mass is thus obtained of a coppery appearance, moistened by water formed during the reaction. Alcohol gives a solution of a magnificent blue colour, with all the properties of a colouring matter. Caustic alkalies precipitate red crystalline flakes, giving crystalline salts with acids, coppery in appearance, insoluble in water, and containing the hexatomic base tricenanthylidene-dirosaniline

( 220

H16,61H7N

No 1307 H formed according to the equation

2N ̧ { ←20H10 + 3¤‚H1,0 =3H2O+Ng (220H16 {H The base furnishes several chloroplatinates, it combines

with weak acids, and even with carbonic acid.

These salts and the hydrate of the base readily decompose below 100° C., especially in the presence of a slight excess of cenanthol, producing a yellow resinous mass containing free acid. The transformation may be effected without the least loss of weight and without disengagement of a gas, if the acid be not very volatile. In its properties the product resembles the compounds obtained by the action of benzoic and oenanthic aldehydes on aniline, toluidine, and toluylene-diamine. In fact, the greater part of the dense mass consists of a resinous diamide, oenanthylidene-ditoluène-diamide

GH N2H=1H26N2• (H14

I have not hitherto succeeded in isolating the diphénylénic diamide which figures in this equation, but the microscopic inspection and chemical analysis of a great number of chloroplatinates puts it beyond doubt that by the decomposition of œnanthic rosaniline at least two amides are formed, one of which must have an equivalent lower than that of the above compound.

The action of benzoic aldehyde, slow at 90°-1000, furnishes, in the first place, a violet mass, which, according to the analyses of chloroplatinate, seems to contain the intermediate compound toluydenic rosaniline €20H16

N37 H=27H23N3.

H

The complete substitution is with difficulty effected at 120°, and gives a crystalline product, copper coloured and possessing almost exactly the properties of the oenanthic compound.

I had hoped that the decomposition of rosaniline by benzoic aldehyde would furnish one of the terms intermediate between hydrobenzamide and amarina, described in a previous note, but its decomposition is not analogous to that of the oenanthic compound. The decomposition in this case takes place very slowly, even at 150° to 160°, and in presence of an excess of benzoic aldehyde. A dense yellow liquid is finally obtained, which gives up its excess of aldehyde on treatment with alcohol, leaving a sandy powder, very little soluble in alcohol and ether, insoluble in caustic alkalies and acids, even when concentrated, but furnishing a chloroplatinate with from 11 to 11.5 per cent. of platinum. The final action of acetic aldehyde on acetate of rosaniline causes the formation of an analogous substance. These substances neither possess the properties of toluenic diamides nor those of a derivative of leucaniline.

In conclusion, I would observe that the products of substitution furnished by aldehydes with rosaniline support the formula by which M. Hofmann denotes the con

nexion between aniline red and blue.

Mineralogical Chemistry; Studies on the Immediate

Analysis of Minerals, by M. G. LECHARTIER.† ANALYSES made by the same chemist, of different varieties of the same kind of mineral, frequently present considerable differences in their results. The cause of this diversity is to be traced to the impurity of the substances analysed. A careful observation of natural crystals shows how difficult it is to obtain an isolated mineral substance. Sometimes these crystals are mixed with foreign matters, sometimes they have undergone a mere or less radical alteration. Often the pure crystals exist only in very small quantities, in rare specimens, to be found only in very few places. When they can be

This amide can hardly be said to possess basic pro- found they serve to determine the chemical composition perties, but it furnishes a yellow chloroplatinate,

€21H26N2.HPt. Cl..

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which will be the typical composition of the whole mineral. But it remains to be shown that the composition of the other varieties which are less pure is identical. Hence the necessity of purifying crystals without altering them. It is at all events needful, by carefully observing the impurities mixed with them, by analysing them, to show cause for the differences between the results obtained and the composition of the mineral type.

M. Ch. Sainte-Claire Deville, in his great work on feldspaths, proves the importance of isolating, by careful sorting, the matter to be analysed. It was by devoting a considerable length of time to this operation that he 'discovered the simple chemical connexion between the + Bulletin de la Société Chimique, 1865.

numerous minerals of this group, and added several varieties to the list, which had been separated from it.

Without these precautions, it would be found necessary, after the most careful analyses of matters supposed to be pure, to admit different compositions for the varieties of the same substance, all having the same crystallographic characteristics, or to admit that two bodies, such as silica and aluminia, are isomorphous, though no fact in chemistry justifies such an hypothesis. The first of these results is produced by the staurotide; the second by amphiboles.

Such are the difficulties which I have endeavoured to overcome by these researches, made in the laboratory of the Ecole Normale Superieure. As a pupil of M. Henri Sainte-Claire Deville, I have endeavoured to apply his lessons, and have throughout been much indebted to his advice.

Ι

Analytical Processes.-I followed exactly M. H. Sainte-Claire Deville's analysis of silicates, described in the Annales de Physique et de Chimie, xxxviii., 5. The purity of the isolated elements, and especially of silica and magnesia, has always been acknowledged. I dissolved the silicate in pure hydrofluoric acid, and obtained crystallised hydrofluate of fluoride of potassium. I slowly evaporated the hydrofluoric liquid with a few drops of sulphuric acid added to it. The sulphates remaining alone in the capsule were calcined at red heat, and the weight of oxides subtracted from the first weight obtained. A similar operation was performed with magnesia, which was dissolved in nitrate of ammonia.

Determination of the degree of Oxidation of Iron in the Silicate.-In the analytical process hitherto employed the mineral is attacked by borax, or boric acid, dissolved in an acid, and protoxide of iron estimated in the solution by means of a standard solution of permanganate of potash. In this operation it is indispensable to avoid oxydising bodies and reducing gases,

and this is very difficult.

I have tried to find a process by which might be determined, by means of the balance, the quantity of oxygen combined with the iron. Were the determination to be made on free oxide of iron, it would suffice to reduce a given weight of dry oxide in a hydrogen

current.

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The oxygen being determined by the difference of weight, all the volatile elements must be eliminated, by heating the mineral to redness in a pure and dry current of nitrogen, and the water, if there be any, collected on coming from the tube and weighed.

At the temperature given by the gas furnace, a reaction takes place between the carbonate of lime and the silicate; carbonic acid is disengaged, and the oxide of iron is reduced. Continue the action of the hydrogen until the weight remains constant. A current of dry air afterwards rapidly oxidises the iron. Fuse the mixture in a platinum crucible, and analyse the glass in the usual way. The weight of iron is determined in the analysis.

Accidental Formation of Sulphide of Silver (Argyrose), by Dr. T. L. PHIPSON, F.C.S.

ABOUT eighteen months ago I filled a silver match-box with the common large French matches which are used in the cafés, &c., at Paris. On my return to London this box lay for many months in a drawer that was rather damp. On opening the box recently, I was surprised to find the inside lined with very brilliant crystals of a black colour and metallic lustre, which reminded me at once of some specimens of silver ore I had received a few months back from the Don Pedro mines of Mexico. I had no doubt these crystals-modified octahedra of the first system-were argyrose (or silver glance) accidentally formed. On examining them with a powerful lens, which enabled me to make a drawing of their crystalline form, and finding afterwards that they contained about 87 per cent. of silver, this supposition proved exact. It is, therefore, not improbable that this mineral may have been formed in nature by the prolonged action of sulphurous vapours upon metallic silver.

On the Strength of Solutions of Phosphoric Acid of
Various Densities," by Mr. JOHN WATTS, Senior Bell
Scholar in the Laboratories of the Pharmaceutical
Society.

THE utility of a table which shows at a glance the per-
centage strength of a solution whose specific gravity is
known, will at once, I think, be admitted by all. The
force of this is shown by the fact that, many years ago,
MM. Bineau and Otto compiled the first table of the
kind, sulphuric acid being the substance operated upon;
this was soon afterwards followed by nitric and hydro-
chloric acids by Dr. Ure; and still more recently by
another for ammonia. The other alkalies, potash and
soda, have also been tabulated by Dalton and Fünner-
mann; acetic acid by Dr. Mohr, and alcohol by
Fownes. These, I believe, are all which, up to the
present time, have been so worked upon.

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Knowing the great advantage such tables present to the practical chemist, more particularly in saving of time and labour, I undertook, as a subject for the Pharmaceutical Conference, to compile a table of phosphoric acid, so as to exhibit at once the relation between its density and its strength. . . Although a table for phosphoric acid is not so indispensable as one for sulphuric or nitric acids, its use in the arts and manufac tures being much more limited, still phosphoric acid is coming into much greater use, at least in medicine, and any one who has had the work of making the "syrup of phosphates" which are now so fashionable, knows the advantage accruing from the possession of a ready means of obtaining a knowledge of the strength of his

To reduce oxide of iron, mix the matter thoroughly with a given weight of pure carbonate of lime, and put the whole in a platinum vessel, previously tared, in a stoppered glass tube. Weigh the mixture, after having dried it at a low temperature. Place the vessel, by means of a slide in a platinum tube, which heat over a gas In the compilation of a table of this furnace. Pass into the apparatus a regular current of kind, the first thing is to know at what specific gravity hydrogen, purified by its passage through a flask filled to start; accordingly, finding that a thick syrupy acid with fragments of potash, and a glass tube containing of 15 sp. gr. contained nearly 50 per cent. real ÞO, I platinum black, heated to a little below nascent red heat.

solution.

* Read at the meeting of the Pharmaceutical Conference.

50% Ho PO4 = 36.4% RO

made that the starting point and proceeded regularly downwards as far as sp. gr. 1'006. The interval between these two numbers contains 47 specific gravities, therefore 49 in all, and as each sp. gr. was analysed at least three times in order to obtain a correct mean, it entailed the work of about 150 analyses. The table, when completed, stands as follows:

Specific Per- Specific Per- Specific Per- Specific Pergravity centage gravity centage gravity centage gravity centage

12.18 10'44+ 9'53 8.62

1464

1453

(1.508 49.60 1369 39°21 1236 27°30 1095
1492 48°41 1356 38.00 1°226 26.36
1'476 47°10 1'347 37 37 1211
45.63 1339 3674 1197 23 23
45°38 1328 36°15 1185 22°07
1442 44 131315 34.82 1173 20°91
1434 43 95 1302 33'49 1*162 1973 1031
1426 43 28 1°293 32°71 1153 18.81 1'022
1418 42 61 1285 31'94 1144 1789 1014
1401 41 60 1276 31.03 1136 16.95 1006
1*392 40.86 1268 30°13 1124 1564
1384 40 12 1257 29°16 1113 14°33
1.376 39.66 1°247 | 28°24 | 1109 13.25

1081

24 79

1'073

1066

1056

1047

7.39
6.17
4:15

3'03
1'91

red lead (2PbO + PbO2), and dissolving out the protoxide with dilute nitric acid, washed well the resulting binoxide; this, by careful ignition over an air-flame, loses its extra oxygen atom, and passes with incandescence to the state of protoxide. Working with oxide prepared in this manner I obtained highly satisfactory results, and subsequently used this method only for the completion of the analysis of the table. By examining the gradation of the numbers on the table, we see that the percentage increases or decreases regularly according as the specific gravity rises or falls, proving that the strength can be correctly deduced from a knowledge of its density and that, unlike acetic acid, it presents no anomaly in this respect; also, that when a strong acid is diluted with water, though a considerable quantity of heat is evolved, no condensation in volume follows. The correctness of the numbers may be also somewhat checked in the following manner :

5

Take 100 fluid grains of 1'508 acid, this will weigh 790 150.8 grs., and contain 74'79 grs. by weight of PO dilute this with 100 fl. grs. of water, the whole will weigh 250.8 grs., and contain 74'79 grs. by weight of PO,; each 100 parts by weight will be therefore of sp. gr. 1254, I would next notice the method employed for its and contain theoretically 29'7 parts by weight of acid; analysis. Now, after essaying and testing the various by referring to the latter sp. gr. on the table, we find advantages of a great many different processes, of which by experiment such number to contain 29.16 per cent. I will speak hereafter, I came to the conclusion that, Again, 100 fl. grs. of acid 1285 sp. gr. will weigh 128.5 with a pure solution of phosphoric acid, no method is grs., and contain 41'03 grs by weight of PO,; diluted more simple, more accurate, or less liable to error, than with 100 fl. grs. of water, will weigh 228'5 grs., and conthe method employed in the British Pharmacopoeia-tain 41'03 grs. of acid, being of sp. gr. 1142; each 100 viz., "the evaporation down of a weighed quantity of the parts of this sp. gr. should contain, then, 17'9 by weight solution, with a known excess of pure protoxide of lead." of POs. Reference to the table shows us 17.89 per cent. I confess I was somewhat disappointed when first em- I have checked a great many numbers in this manner, ploying this method, owing to the discordant results and they all come correct. obtained, notwithstanding that at first sight it seems ex. ceedingly straightforward and plain; but I afterwards found it entirely arose from not operating with pure oxide. I had used the commercial article, and though previous to each analysis it had been carefully ignited, there nevertheless remained so much carbonate and other

impurities, as to render it practically worthless, no two results agreeing nearer than 2 or 3 per cent.

Finding this to be the case, I looked about for some other substance to use instead, and for this purpose tried the oxide of zinc. Analysis with this latter oxide gave perfectly accurate results as regards numbers, but was, however, open to a great objection, inasmuch as the phosphate of zinc formed readily fuses, and upon ignition towards the end of the analysis to get rid of the last traces of water, the phosphate fusing, and adhering tenaciously to the bottom of the crucible, from which it cannot be subsequently removed, entirely spoils it for a second operation. Oxide of magnesia answered no better, for this, unlike the oxides of lead and zinc, forms a hydrate when put into water; and, as is the case with many magnesia salts, either the last traces of this water of hydration, or the atom of basic water assimilated when neutralising the PO, is so difficult to totally expel, even after powerful ignition, that one can never be certain that the whole of the water is driven off unless the capsule has been allowed to cool and re-ignited several times, which, with such a number of similar analyses, causes much unnecessary trouble. I tried also the volumetric nitrate of uranium process, but as the results never approach nearer than five to six per cent., a discrepancy too great to be allowed in a case like this, it was given up... Determined then to revert again to oxide of lead, and to prepare a pure oxide myself, I took

† Ph. Br.

The temperature at which all the specific gravities were taken was 15.5 C. (60° Fahr.). This is, of course, an important point in using the table, as the volume of liquid varies considerably according to the temperature; and as at different heights of the thermometer comparison of volumes no longer holds good, consequently comparison of percentages would be equally fallacious. Very little more remains to be said, as this is not a comprehensive subject which requires much dwelling upon. I might add that the acid used was prepared from common phosphorus in the ordinary manner; but I have since made several samples of acid from amorphous phosphorus as first mentioned by Mr. Groves, and decidedly prefer this latter method; the phosphorus is readily acted upon, entails no danger in the process, and a product is obtained in a few hours which ordinari.y would take as many days. One little objection appeared, which is apt to make one think that the product is not absolutely pure, viz., that in the concentrated state it was more or less coloured, possessing a brownish or yellow tint; this might have arisen from the particular specimen of amorphous phosphorus operated upon : probably another sample would not show this defect.

Lastly, I think I have shown, as far as practicable, the corrections of the table in question; and I know this, that in quantitative analysis generally, and more especially when work is published for the use or guidance of others, as in the present instance, it behoves me to accept only thoroughly-substantiated and verified results, else an incorrect analysis, while it brings one's own name into disrepute, at the same time misleads and falsifies the labours of others. It only remains now to be seen whether the table prove in practice as useful as it was anticipated to be.

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