222

Ether seems to preserve it, a fact which has been known for some time. This was also mentioned to me by Dr. Messel, of Silvertown, in August, 1878, a method I have used ever since. It is stated in all our text-books that peroxide of hydrogen is neutral to test-papers. Now, all commercial peroxide is faintly acid with the excess of hydrofluoric or hydrofluosilicic which is added and which should be estimated in each sample before using it. I have used peroxide of hydrogen since 1873, and latterly in comparatively large quantities, and I have made it a rule to examine each purchase as follows:100 c.c. of the peroxide was evaporated to dryness with 10 c.c. N soda, ignited, and taken up again with water. N acid was then added to neutrality, chromate of potash, and finally titrated with nitrate of silver. The results

N

ΙΟ

of many experiments upon this one sample showed that 100 c.c. of peroxide neutralised o2 c.c. of N soda and

N

10

consumed 3'4 c.c. of nitrate of silver. On the evaporation to dryness of the peroxide by itself a very pungent acid is liberated, and which can be easily told is not hydrochloric. In order to show the moderate stability of peroxide of hydrogen, I have lately had a sample sent me of commercial peroxide which was at least fifteen months old. When treated with bichromate over mercury it gave 7 volumes of oxygen, and I know that no special care, or indeed care of any kind, was bestowed upon the sample.

Having, then, a ready method of testing its contained amount of active material, it remains only for me to show that peroxide of hydrogen is an exceedingly useful oxidising agent, for it oxidises by reason of its loosely combined oxygen, and when an excess is added to any substance or to any solution, that excess is readily eliminated, leaving only as a residue that most neutral substance water.

There are many substances often seen in the laboratories of alkali works that cannot be readily and accurately examined except by its use; such as the total alkali and crude soda liquors or in black-ash, and certain qualities of soda-ash which contain sulphides or sulphites. In the testing of chamber exits it is extremely useful, inasmuch as sulphurous acid is not an acid easily titrated, for the normal sulphite of an alkali is not neutral to test-paper, and therefore on titrating a sulphite with a standard acid the point of neutrality is not clearly defined and distinct. This want of clearness in the ending has been stated by some chemists to be due to the carbonic and nitrous acids

{CHEMICAL NEWS

May 23, 1879.

present in chamber exits, but add peroxide of hydrogen to the solution and all difficulty vanishes, the sulphurous acid is oxidised to sulphuric, which acid is easily titrated. I will now proceed to give examples of its use in various methods of analysis. Some samples of soda-ash contain so much sulphite of soda that it is impossible to estimate the amount of alkali accurately by means of standard acid. As an example of this kind of ash I give the following analysis of a sample of ash made from caustic salts, which contained by the acid test in the ordinary way 30 per cent of alkali without peroxide of hydrogen, whilst the addition of a few c.c. brought down the actual percentage to 21. The escaping carbonic acid carries away a great deal of sulphurous acid, but it does not do this if peroxide of hydrogen is present.

black-ash; a few c.c. added to the liquor under examinaPeroxide of hydrogen is very useful in the analysis of tion gives at once the total alkali, which number needs no correction for sulphides, hyposulphites, &c.

tions, such as the oxidation of iron salts, colouring This reagent is very useful for many laboratory oxida applications of this useful substance are legion. I first matters, experiments on bleachings, &c., &c. In fact the commenced to use this reagent for testing vitriol exits in 1873; but its application then was very limited as I had to make my own, and a perfectly pure peroxide of barium is not peroxide of hydrogen was looked upon as a sort of rara a very easy thing to make. In those days avis, to be found only in the laboratories of schools of chemistry, and its use was not much extended until a pure peroxide of hydrogen entered the market as a commercial article, to be bought and sold in the same way as other reagents.

Heaton Chapel, May 12, 1879.

EXPLOSIONS IN FLOUR-MILLS AND COALMINES.

By WATSON SMITH, F.C.S., F.I.C.

I BELIEVE it was about the year 1871 that the great explo. sion took place at the Tradeston Flour Mills, near Glasgow, but not having any particulars with me here, I cannot speak with absolute certainty as to exact date. As this was a catastrophe attended with loss of life and great damage to property, a searching investigation was made into its causes. Several theories were propounded, but none appeared to be satisfactory or to meet the circumstances but the one which I was enabled to give. This explanation was suggested to me on reading a short note in Dingler's Polytechnisches Journal, of which an abstract appeared under the head of "Technical Chemistry” in the Journal of the Chemical Society. The author, who wrote from Austro-Hungary I believe, had noticed how artificial lightning was made in theatres by blowing lycopodium seed through a flame, and he found that dry flour would also do for the purpose. 1 hen he argued that flourdust in quantity might also be caused to flash off, given a due admixture of air and the introduction of a spark or flame. In this way he sought to account for sundry explo sions in flour-mills in his part of the world. The sparks might be struck by the stones coming into slight collision, or incautious approach with a naked flame might fire the

NEWS

mixed atmosphere of the stive-room in a flour-mill. The explanation I gave, which appeared in the Glasgow Herald, was based on this, and, so far as I know, I think I may claim priority as to the bringing forward of this view, as far as either Great Britain or America are concerned; at least I understood the Scottish Royal Society's Commission of Inquiry on the subject gave me at the time the credit of it. The drift of my explanation was the following:"If the grinding-stones be supposed to get slightly out of gear at any time, as they quite possibly may, they may come in contact with each other so as to strike sparks amongst the fine flour-dust suspended cloud-like in the atmosphere immediately in the neighbourhood of the stones. Such an attenuated combustible mixture as flourdust suspended in air approaches the condition of a mixed gas, and, the proportions being favourable, an explosive mixture. The whole atmosphere of the stive-room is often laden with this dust. Now, imagine a single grain of flourdust inflamed by contact with a spark from the stones, or by a naked flame brought into the room, what is to hinder this inflammation from passing instantly, and like a flash, from grain to grain, the atmospheric oxygen supplying a common means of combustion? quite analogously to the case of an explosive gaseous mixture. Carbonic acid and steam are thus generated suddenly, and at an elevated temperature, and the sudden expansion in a closed space, like the interior of a mill, produces the pressure resulting in disastrous explosive effects."

Berthelot has calculated that the sudden increase of volume which may take place is amply sufficient to account for explosions. Under certain normal condition, in which great rapidity in the revolution of the stones is attained, and the grain is unusually dry, one can even, with Mr. L. Smith, conceive that sufficient heat may be developed to cause ignition, especially if some hard foreign body-such as a piece of wood, for instance-by any accident should get in with the grain in grinding. Its attrition and pulverisation might, perhaps, cause ignition of the dust produced. Still, an abnormal rapidity of revolution would also, in case of slight collisions of the stones, cause showers of sparks to fly, or an ordinary lantern or bare flame might be brought into the room, and these would be quite sufficient to inflame the atmosphere, given favourable proportions of flour-dust and air existent at the time. This it seems to me is an explanation nearer at hand, and also more probable than the other.

Mr. Langbeck in his paper (CHEMICAL NEWS, vol. xxxix., p. 191), though thinking himself justified "in opposing these explanations and substituting another one," neither, in point of fact, does practically oppose them, nor does he offer anything in substitution but an unlikely surmise-a mere "smell of impure hydrogen," on which opinions again might differ. This surmise he tries to support by experiments, which, however, on the whole, go more to second the explanations already given above than his own. The experiment with the coal-gas, as recorded, is abortive to prove anything on the subject; and, finally, his opposition to the explanation given, and his substitution of another one is a complete fiasco, for he winds up asking the way to the source of his own surmise. Having attained this, but failing to find his way out of it again, he puts it to the reader to find the way out for him in a couple of questions further. And this is opposing an explanation and finding a substitute! To both questions I for one would reply "Certainly, No! as far as the case in point is concerned." If one of them were admissible it might surely be expected that explosions should occa. sionally be heard of in our bakers' ovens. Perhaps Mr. Langbeck is not aware that a well authenticated explosion is on record caused by the falling of the contents of a flour-sack. The cloud of flour-dust came in contact with a gas-flame, and a very considerable explosion occurred. The Journal of the Chemical Society of London for this month contains a brief account of Berthelot's views on the subject.

It is is now a pretty well ascertained fact that some

otherwise slight coal-mine explosions may be expanded into great disasters, owing to the clouds of coal-dust raised into and diffused through the atmosphere of the workings; such an atmosphere, especially in presence of traces of firedamp, being thus suddenly converted into an explosive mixture. This view, too, explains the frequently observed fact that an explosion in a coal mine often sweeps over very considerable tracts of the workings. I am told that Prof. Marreco, of Newcastle, has investigated and experimented on this subject.

It has occurred to me that in view of these similar causes of, and liability to, explosions, both in flour-mills and in coal-mines, the electric lamp would be the best and safest means of illumination that could be employed. Such a light could be confined in a glass globe, hermetically sealed, and would be a fixture of course. Means of signalling could also be adjusted in coal-mines. Thus most stringent and rigorous measures would be rendered feasible to prevent the introduction of matches, lights, or lamps and lanterns of any kind into the workings. At the present cost of the electric lamp it might also with advantage be used in the stive-room of flour-mills, and others where clouds of flour-dust may be raised at any time. This recommendation may of course have been already made; if so I have not observed it, and on this ground may plead excuse for failing to acknowledge prior claims. Zürich, May 9, 1879.

PROCEEDINGS OF SOCIETIES.

CHEMICAL SOCIETY. Thursday, May 15, 1879.

Dr. WARREN DE LA RUE, President, in the Chair.

THE minutes of the previous meeting were read and confirmed. The following certificates were read for the first time :-C. J. Wilson, G. S. V. Wills, W. H. Kerr, G. R. Tweedie.

The PRESIDENT then called on Mr. WARINGTON to read a paper On Nitrification (Part II.)." A. Müller was the first to advance the opinion (Chem. Soc. Journ., 1873, 1267) that nitrification is due to the action of a ferment. Schloesing and Müntz proved this to be the case (see Part I. of the author's paper), and from recent experiments show that soils which induce nitrification have this power destroyed by exposure for one hour to 100° C., and that ordinary moulds and mycoderms injure rather than promote nitrification. The author also mentioned that the above experimenters were at present engaged in an attempt to isolate and cultivate the organism, which promised good results. The objects of the author were to ascertain the influence of light, temperature, variations in the composition, and concentration of the solutions on the process of nitrification, the rate at which it progresses, and the relation of the nitric acid produced to the ammonia consumed. In nearly every case exposure to light prevents nitrification, and in all cases the exposure hindered the process to a marked extent. The mould which develops in a solution containing tartrates is incapable of effectting nitrification. The presence of carbonate of calcium seems to be indispensable to the growth of the ferment. The author pointed out the significance of this fact as explaining the absence of nitrites and nitrates in soft peaty waters, and as bearing on the utility of applying lime, &c., to peaty soils rich in nitrogen, in a form unfavourable for absorption by plants. A very small amount of organic carbon is requisite. An extensive series of quantitative experiments is given as to the effect of temperature. The upper limit of temperature at which nitrification takes place has not been determined. 40° C. is,

however, fatal to the process, which can proceed at 10°, and probably at still lower temperatures. In all cases there is a period after the addition of the ferment during which no appreciable effect is produced. This period the author terms the period of incubation. This period is considerably shortened by increasing the temperature. Thus, in a solution containing 640 milligrms. AmC1 per litre the period was at 10° 78 days; at 30°, 19 days. As the solutions become stronger the period increases. Thus, a solution containing 80 milligrms. the period was only 31 days at 10°, or 12 at 30°, instead of as above 78° and 19°. The presence of bacteria does not promote nitrification. The author discusses the interesting question why in some cases nitrites, and in others nitrates, are produced. When the ammonia disappears before the nitrous acid is converted into nitric acid, the nitrites left in solution are very stable if, however, the oxidation of nitrites sets in before the ammonia has been consumed nitrates are formed with great rapidity. In no case is the whole of the ammonia obtained as nitric acid. Some experiments were made as to the part played by the heating effect of the sun's rays in preventing nitrification, as a temperature of 40 proved to be fatal. It was found that a solution sheltered partially from the heat, by a screen of alum solution, but fully exposed to the light, of the sun, nitrified sooner than a similar solution exposed to the heat and light. In both cases nitrites were formed which were very permanent. The paper concludes with some interesting experiments on the conversion of nitrites into nitrates by the ferment. This change apparently takes place only in the dark, and a ferment which is quite competent to convert ammonia salts into nitrites is apparently not necessarily competent to convert the nitrites into nitrates. Some solutions, however, which are nitrifying seem to possess this power in a high degree. The progress of nitrification is not uniform; it begins slowly, increases in rapidity, and after reaching a maximum again diminishes. The strongest solutions nitrified by the author contained 180 parts of nitrogen per million.

The PRESIDENT said the author had investigated the subject with great acumen. It was interesting to observe that the process might produce either nitrites or nitrates. Dr. WRIGHT then read a paper "On the Alkaloids of the Veratrum Family (Part III)," by C. R. A. WRIGHT and A. P. LUFF. Alkaloids of Veratrum album.-The authors have examined the alkaloids extracted from 12 kilus. of dried roots hy percolating with alcohol acidified by tartaric acid (1 part per 200 of roets), evaporating to a small bulk, addition of water, filtration from resin, and treating with a slight excess of caustic soda and ether. After repeated washing with ether an insoluble precipitate was left, which seemed to consist principally of a base hitherto undescribed, which the authors name pseudojervine, C29H43NO7. It is snow-white, and melts at 299; crystallising anhydrous from alcohol; with sulphuric acid it gives a yellow solution, gradually turning green. The ethereal solution contains, besides small quantities of pseudo-jervine, several other alkaloids, which can be separated by shaking the crude ethereal solution with aqueous tartaric acid, and treating the mixed tartrates with soda and a smaller bulk of ether: a residue is left, containing pseudo-jervine, an amorphous alkaloid named by the authors Veratralbine, and Jervine. Jervine, C26H37NO3, forms a sulphate almost insoluble in hot and cold water. It crystallises with two molecules of water, melts at 239°, and gives with sulphuric acid the same colours as pseudo-jervine; the sulphate of pseudo-jervine is, how: ever, tolerably soluble in water. The second ethereal solution deposits on spontaneous evaporation crystals of jervine mixed with another base, which forms a readily soluble sulphate. This base gives with sulphuric acid a red colouration, hence the authors suggest the name Rubijervine. It melts at 237, and resembles in many respects pseudo-jervine; forms with crystallised salts, and crystallises anhydrous as C26H43NO2. The ethereal motherliquor of these crystals dries up to a varnish consisting

{CHEMICAL NEWS,

May 23, 1879.

chiefly of veratralbine, C28H43NO5. A small quantity of another base is present, yielding veratric acid on saponification. The mixture of veratralbine and this base is powerfully sternutatory, but this property is lost by boiling with alcoholic potash. Hence it is probable that the sternutatory constituent is veratrine (Couerbe). Neither jervine, pseudo-jervine, rubi-jervine, nor veratralbine excite sneezing. Veratralbine gives with sulphuric acid a red colouration resembling that given by cevadin and veratrine. No evidence of saponification or other decompositions was obtained on boiling these bases with alcoholic potash, the minute quantity of supposed veratrine excepted.

Dr. WRIGHT then read a paper "On the Alkaloids of the Veratrums (Part IV.)." Alkaloids of Veratrum viride. On treating about 18 kilos. of dried roots precisely as described in the foregoing paper, the first treatment with ether left undissolved some pseudo-jervine, the tartrates obtained from the ethereal solution yielded no veratralbine, but jervine crystallised out from the second ethereal solution on standing. Traces of rubijervine were observed. The ethereal mother-liquors dried up to a powerfully sternutatory amorphous mass, closely resembling the "veratralbine" similarly obtained from V. album roots. It gave on analysis, however, C32H49 NO9, the formula of cevadin, and on saponification it yielded about the theoretical quantity of cevadic acid with a trace of veratric acid. The following table represents the approximate yield of the different bases from the two roots per kilo. :V. album.

V. viride.

The jervine and pseudo-jervine from V. viride agreed in melting-point, properties, analytical numbers, &c., with the specimens obtained from V. Album.

of the Aconites (Part IV.)," by C. R. A. WRIGHT and A. Dr. WRIGHT then read a third paper "On the Alkaloids P. LUFF. Japanese aconite roots.-The authors have exalcohol acidulated with tartaric acid, evaporating, adding amined two different batches of roots, treating them with water, making alkaline with sodium carbonate, and then shaking with ether. Repeated treatments with ether failed to dissolve all the alkaloid present, some being obstinately retained by the alkaline fluid; this appeared to be nonshaking with aqueous tartaric acid and treatment of the crystalline. The ethereal extract, after purification by crude tartrate solution with soda and fresh ether, gave by spontaneous evaporation crops of crystals. These crops indicating the formula C66H88N2021. Treatment with hot were fractionated and re-crystallised; all gave numbers concentrated tartaric acid failed to produce any change in the analytical numbers, whence the authors conclude that the substance is not a mixture of two bases, C33 H45 NOII and C33H4,NO10. The authors have named this base Japaconitine. It melts at 185° to 186°, and closely resembles aconitine. On saponification it splits up into benzoic acid and a new base, Japaconin. Japaconin closely resembles aconin, but on treatment with benzoic anhydride it forms a tetrabenzoylated instead of a dibenzoylated derivative. A tetrabenzoylated body is also formed by heating japaconitine with benzoic anhydride, aconitine giving a dibenzoylated body. The authors adopt the following view as to the constitution of japaconitine, admitting the existence of a base—

NEWS

Japanese aconite roots have already been examined by Paul and Kingzett, who isolated a crystallisable base from a small quantity of roots, which gave them numbers on combustion compatible with the substance being either pseudaconitine or japaconitine. Unfortunately the small yield did not enable them to fix its molecular weight by an examination of the gold-salt, and consequently they adopted the formula C29H43NO9 from combustions and nitrogen determinations by volume. Their description of the base as not forming crystallised salts would rather indicate that it was pseudaconitin. On the other hand, on boiling with dilute sulphuric acid, a solution was obtained which reduced Fehling's solution. This reaction does not occur with pure pseudaconitine, although aconitine and japaconitine yield saponification-products capable of reducing Fehling's solution.

In an appendix to the foregoing paper C. R. A. WRIGHT and A. E. MENKE describe experiments made to isolate if possible the hypothetical parent base referred to in the previous paper. I cwt. of roots was worked up without adding any tartaric acid to the alcohol to prevent, if possible, dehydration. The crystallisable base obtained was separated into several fractions, but all these gave the formula C66H88N2O21; so that if the supposed parent base really exists in the roots, it must be much more easily dehydrated by heat, &c., during extraction than either aconitine or pseudaconitine. In this and the other batches of roots extracted the authors confirm the observations of Paul and Kingzett as to the yield of alkaloids from Japanese aconite, being nearly three times as great as that obtained under similar circumstances from a good commercial sample of Aconitum napellus. The crystallised japaconitin equals about 1 grm. per kilo., and the total yield of alkaloids being 2 grms. per kilo., besides which about I grm. of amorphous bases is retained in the alkaline liquors after repeated treatment with ether.

Mr. KINGZETT said that the Japanese aconite roots examined by Dr. Paul and himself were given to them by Mr. Holmes to determine what alkaloids were present in these roots, and whether their composition agreed

As a

with that of the alkaloids from other aconite roots. result of their investigation they obtain a small quantity of a very pure alkaloid, quite crystalline, which had undoubtedly the formula C29H43NO9. The nitrogen was determined by volume, a process which in his opinion was more accurate than the soda-lime method. He could not agree with Dr. Wright in considering the formula wrong, though the base did not form crystallised salts. On a previous occasion Dr. Wright had stated that their alkaloid was pseudaconitin. This statement was now withdrawn. They had obtained conclusive evidence of the existence of two alkaloids.

Dr. WRIGHT, in reply, said that he was not convinced as to the identity or otherwise of his alkaloid and the one obtained by Paul and Kingzett. From the data given by the above authors he had stated that the properties, &c., of their alkaloid agreed with those of pseudaconitin, and he still held to this statement. He had only withdrawn it as far as his own alkaloid was concerned, which was certainly not pseudaconitin. He did not dispute the accuracy of nitrogen determinations by volume, but if only 2 per

cent of nitrogen was present the method was not delicate enough; the only plan was to obtain gold or platinum salts. "On the

The next paper was read by S. U. PICKERING, Action of Hydrochloric Acid on Manganese Dioxide." The principal object of this paper is to criticise the conclusions drawn by W. W. Fisher in a paper "On Manganese Tetrachloride (Chem. Soc. Journ., September, 1878). The only conclusion at which the author arrives in common with Fisher is that when manganese dioxide is treated with cold concentrated hydrochloric acid it dissolves, forming a dark brown liquid, which evolves chlorine slowly at ordinary temperatures, and more quickly when heated. The points in Fisher's paper are stated by the author to be:-That from the liquid obtained as above, water always precipitates a definite substance, which is manganese dioxide; that the ratio which the precipitated manganese bears to the loosely combined chlorine of the higher chloride from which it is precipiis as 12 atoms; that this higher chloride is MnCl4. The experiments, details of which are given in the present paper of 42 pages, prove, in the author's opinion, conclusively, that from a solution of manganese dioxide in cold hydrochloric acid, water does not precipitate a definite substance; that the substance precipitated is not manganese dioxide, but a mixture of the dioxide with the sesquioxide in variable proportions; that the ratio which the precipitated manganese bears to the available chlorine of the choride from which it is precipitated is not 1: 2 atoms; that the higher chloride produced is not MnCl4 but Mn2C16. The author in conclusion sums up briefly the main points proved in his paper as follows:When a solution of manganese dioxide in strong hydrochloric acid is diluted with water, a mixture of oxides is precipitated which is indefinite in composition, varying between 30MnO2,5MnO and 36MnO2,5MnO. The manganese contained in this precipitate as dioxide bears to the loosely combined chlorine of the higher chloride from which it is precipitated the ratio : 2 atoms. The total manganese precipitated therefore bears to this chlorine the ratio of about 1: 174 atoms. When the solution of the dioxide is performed in weaker acids the amount of the higher chloride formed is not appreciably diminished. An increase in the actual amount of the aqueous acid employed for the solution is prejudicial to the stability of the higher chloride formed; the solution of the dioxide and sesquioxide by hydrochloric acid, and the subsequent decomposition of the sesquichloride, being represented by the following equations :

-

(1.) Mn2O3+6HCl=Mn2C16+3H2O.

(2.) 2MnO2+8HCl = Mn2C16+ Cl2+4H2O.
x{Mn2C16+2H2O=MnO2+MnCl2+4HC1}
y {Mn2C16+3H2O=Mn2O3+6HCI }

xy being usually as 6 to I.

The SECRETARY then read a "Preliminary Note on some Reactions of the Ammonio-chloride of Magnesium known as Magnesia Mixture," by H. D'ARCY POWER. The author has observed that most potassium and some sodium salts precipitate magnesium hydrate from a solution of ammonio-chloride of magnesium. Potassium iodide possesses this property in a marked degree. Thus the addition of 15 c.c. of a 10 per cent solution of potassium iodide with 10 c.c. of ammonia to 5 c.c. of magnesia mixture (prepared by dissolving 5 grms. of magnesium oxide in 40 c.c. of hydrochloric acid, and then adding 60 c.c. of ammonia and filtering), after standing twentyfour hours gave a precipitate which, when washed and ignited, weighed o'046 grm.; it was pure MgO, so that 46 per cent of the total MgO was precipitated. Potassium bromide gave under similar circumstances a precipitate weighing o'002 grm. Further results are promised.

226

The two following papers were taken as read:

The Composition of Cows' Milk in Health and Disease," by A. WYNTER BLYTH. The results of this research are the separation of two alkaloidal bodies as normal constituents of milk; the separation of a substance, probably a glucoside, derived from plants, &c, eaten by the cow; a quantitative estimation of the different constituents of milk; analyses of samples of milk derived from cattle in an unhealthy state. The separation of the milk alkaloids :-A litre of milk is divided into three equal parts, to one of which a litre of water is added, the casein is precipitated in a flocculent condition by the cautious addition of acetic acid, and, finally, by passing carbonic acid, a clear yellow whey is obtained, which is separated by decantation and filtration and used to precipitate the second portion; the whey from this is similarly used to precipitate the third portion of milk. The yellow whey is boiled and filtered to get rid of albumen, and to the filtrate an excess of the solution of nitrate of mercury used for urea estimation is added. The precipitate which falls contains the two alkaloids, any albumen, and urea as mercury compounds. It is washed and decomposed with sulphuretted hydrogen, &c. The first alkaloid, which the author proposes to call Galactine, is thrown down by acetate of lead; the lead salt has the composition (PbO)23C54H78N4O45. Galactine is a white, brittle, neutral, tasteless, non-crystalline mass, soluble in water, insoluble in alcohol; it is precipitated by Sonnenschein's and Scheibler's reagents. Excess of lead used to precipitate the galactine is removed and nitrate of mercury added, which throws down an alkaloidal colouring matter. Lactochrome, the empirical formula of the mercury salt, HgOC6H18NO6. Lactochrome is a bright red-orange resinous body, softening at 100°, soluble in water and hot alcohol. In addition to these alkaloids the author has separated two substances. CH305 and C3H3O4, reducing copper solution, which he regards as decomposition products of one substance, and as derived from food eaten by the cow. They are obtained by precipitation with ammonia and tannin, after separating the above alkaloids. The author gives the following as the average composition of healthy cow's milk:-Milk-fat, 3.50 per cent (oleine, 1'477; stearin and palmitin, 175; butyrin, o 270; caproin, caprylin, and rutin, 0'003); casein, 3'93; albumen, 077; milk-sugar, 4'00; galactine, o'17; lactochrome, not determined; bitter principle, o'or; urea, trace; ash, o'70 (K2O, 01228; Na2O, o'0868; CaO, o'1608; Fe2O3, 0·0005; P2O5, 01922; Cl, o'1146; MgO, o'0243); water, 86 87. As regards milk from diseased cows the author concludes that a cow suffering from even very acute disease may give milk differing in no essential feature from normal milk, whilst local affections of the udder may often be easily recognised. Analyses of milk from cows suffering from mammitis, pneumonia, phthisis, &c., are given.

"Notes on the Effect of Alcohol on Saliva and on the Chemistry of Digestion," by W. H. WATSON. The author finds that ptyalin is more rapidly or effectually precipitated from simple aqueous solutions than from saliva. The separation is aided by heating to 100° F.

CHEMICAL NEWS

{CHEMICAL, 1879.

The Society adjourned to June 5, when the following papers will be read: -"On Gardenin," by Dr. Stenhouse and Mr. Groves; "On the Theory of the Fractional Distillation," by F. D. Brown; On the Action of Organozinc Compounds on Quinons," by F. R. Japp; "On Chlorstannic Acid," by J. W. Mallet; "On Indigo-purpurin and Indirubin," by E. Schunck; "Third Report to the Chemical Society on some Points in Chemical Dynamics," by Dr. Wright and Messrs. Luff and Rennie.

CORRESPONDENCE

DETERMINATION OF NITRIC AND NITROUS ACID.

To the Editor of the Chemical News. SIR,-In the CHEMICAL NEWS, vol. xxxix., p. 205, Mr. Davis quotes a remark of mine on Crum's mercury method (which Mr. Davis calls his method, although it was pubblished many years ago, and used by several chemists previously), as if I had not rendered justice to him. I had certainly pointed out that the correction for temperature and pressure is required for something less than "extreme accuracy," as Mr. Davis has put it, considering that it amounts sometimes to more than 10 per cent, and I do not see that I can retract that. I have lately published tables which allow these corrections to be made by a simple read. ing off, without any calculation (Dingler's Journal, vol. ccxxxi., p. 522).

With reference to Mr. Warington's paper, read before the Chemical Society at its last meeting, I beg to point out that in the Berliner Berichte, vol. xi., p. 439, I have described a number of tests, proving the accuracy of Crum's mercury method for nitrous and nitric acid, for a mixture of both, and for mixtures with arsenious acid and with glucose. In the just-quoted paper in Dingler's Journal I have described some precautions required for correctly working the process with my "Nitrometer."

Although Mr. Davis cannot in any sense claim the process as his, yet I have to thank him for bringing it forward again, as I had entirely overlooked it before, and I believe alkali works' chemists were generally in the same situation, and are equally indebted to Mr. Davis.

Would you kindly allow me on this occasion to correct an omission of a few words in my letter, printed in your issue of the 2nd inst., which obscures the meaning of the passage. On p. 194, col. 2, line 5, it should stand-"The total loss of nitre, apart from that in the chambers them. selves." That this is the meaning of the passage is proved by the sequel.-I am, &c., GEORGE LUNGE.

Technical Laboratory of the Federal
Polytechnic Schools, Zürich,

of absolute alcohol added to 200 grs. of saliva and 10 grs. of starch produced in an hour less extractive matter by about one-quarter than a similar mixture containing no alcohol; a similar reduction in the quantity of sugar produced was also effected by the addition of alcohol. The author made some experiments as to the effect of slightly acidulating the mixture of starch and saliva with hydrochloric acid. He arrived at the following conclusions:-By the addition of a small amount of acid the action of the saliva is decidedly increased, while the retarding influence of alcohol is not lessened by the presence of the acid. He also points out the bearing of these experiments on the process of digestion in the stomach, where the starchy matters and saliva are mixed with the gastric juice.

During the reading of the last three papers Dr. GILBERT took the Chair.

CHARGING OF PYRITES FURNACES.

To the Editor of the Chemical News. SIR,-Having erected a set of new furnaces and acid plant seven years ago in the neighbourhood of a town where some of the local authorities were hostile to the manu facture, it was therefore of the greatest importance to prevent any escape of sulphur-gases. I was led to study the best means of preventing the escape during the time of charging. I hit upon a very simple and efficient plan, which had the recommendation of costing nothing. It was simply to close all the ash-pit doors before the door of the furnace to be charged was opened. The neces sary draught being forced to enter through the only open door entirely prevents the escape of gas, and the workman