money value on the manure, but merely term it "a very valuable manure," which may fairly be said of it or of any other manure worth more than £5 per ton; and Dr. Voelcker's recommendation is judiciously qualified by the proviso "if it can be sold at a reasonable price." The manure is said to consist of a " basis" of Peruvian Government guano, but, at any rate, it contains," amongst other ingredients," superphosphate of lime, which is of lower value than that guano.*

CORRESPONDENCE.

NOTES ON LECTURE EXPERIMENTS.

To the Editor of the Chemical News. SIR,-Some time ago I called attention to the subject of lecture experiments, and stated that it would be of great service to those engaged in the work of science teaching if occasionally hints were thrown out in the columns of your journal for the proper performance of such experiments as one meets with in ordinary manuals, but which, in the majority of cases, are most incompletely put before the reader, as those who attempt to repeat the experiments soon discover. It is true the experimenter may soon find out the cause of failure and remove it, especially if he be one accustomed to lecture demonstration, but there is surely no necessity for hundreds of persons each to overcome the same difficulties, when a few lines in this column from any one of them would save trouble to the whole. Lecture experiments or more properly demonstrations are invaluable as a means of impressing facts upon the minds of students in science, and it appears to me that sufficient importance is not given to them in manuals. Besides this, as an additional and perhaps more weighty argument for a column specially devoted to lecture experiments, there are continually new modes of demonstration being devised, but for want of a recognised journal in which to record them they are lost, except to the few who may have been present when they were exhibited.

I would venture to ask you, sir, in the name of myself and several of my friends who are engaged in science teaching if you would allow a column occasionally in your journal for notes and queries respecting lecture experiments not doubting, from the reasons I have given above, that by so doing you would be conferring a favour on a large number of your readers.—I am, &c.,

Midland Institute.

C. J. WOODWARD.

SPURIOUS GUANO.

To the Editor of the Chemical News. SIR,-In reply to the objections raised by your correspondents, Messrs. Rees, to my remarks on this subject, I beg to say that those remarks were based upon the analysis and account given of the manure by themselves; that in those remarks there was not anything either "unor set against " the analysis and reports warrantable" since published in your columns, which confirm, as might have been expected, the analysis by Mr. Ogston, and furnish the most complete justification I could wish for of my estimate as to the value of the manure.

The analysis and reports on this manure do not bear out the assertion that "it is undoubtedly the most valuable that has yet been offered to the farmer," or the statement that the chemists referred to give "the highest opinions of the value of this manure, nor do they accord with the statement that, in reference to its composition, it is a cheap

As my friend, Mr. Ogston, has thought it necessary to say a few words in reply to me, the fitness of which, from his point of view, I can appreciate, and am quite willing to admit, it is with much regret that I see he has gone out of the way to charge me with having made a very unjustifiable attack upon his clients, and to misrepresent me as having stated there was "no Peruvian guano at all" in the manure. No such statement was made by me. Mr. Ogston is also in error in stating that Dr. Voelcker, Professor Anderson, Mr. Way, Mr. Sibson, and himself, differ from me on all points. This is not the case; for the analyses of those gentlemen are, in fact, the basis and justification of my opinion. Mr. Ogston has, of course, full right to hold or express a different opinion, but I venture to think he is not justified in presuming to assert that I cannot be familiar with the subject on which I wrote, and in doing this he has gone beyond his province. Mr. Ogston, I am sure, is sufficiently conversant with the value of manures that, if his client were a farmer, he would not assign to a manure having the composition represented by his analysis a value of £11 per ton; and I do not believe that in any case he would have certified such to be the case.-I am, &c., B. H. PAUL.

8, Gray's Inn Square, March 6th, 1869.

CHEMISTRY OF SUGAR REFINING.

To the Editor of the Chemical News. SIR,-In No. 472 of volume xviii. of your excellent publication is an able and exhaustive paper by Dr. Wallace, On the Chemistry of Sugar Manufacture and Sugar Refining," wherein occurs a passage to which exception must be taken, as it is of a nature to create false impressions.

which invert cane sugar, and enable liquors to dissolve After speaking of the injurious action of weak acids, iron from animal charcoal and from iron tanks and cisterns, besides other impurities, Dr. Wallace adds, “In this way Mr. Beanes's process for treating animal charcoal with hydrochloric acid gas, although otherwise all that can be desired, has entirely failed, and has caused ruinous expense to some refiners who have used it."

While admitting the premises of Dr. Wallace, I fail to see how he arrives at his conclusion. Were it true that Mr. Beanes's process produces weak acids, the conclusion would be perfectly legitimate.

I feel authorised to speak on the subject of Mr. Beanes's process for purifying bone-black. I was one of the first in the United States who became acquainted with the process, and for the last two years I have had charge of it at the refinery of Messrs. Havemeyers and Elder, in Brooklyn, E.D., opposite New York. They refine 100 tons of sugar daily, and treat weekly 220,000 lbs. of boneblack by the process of Mr. Beanes. They have now three large apparatus for making the hydrochloric acid gas in constant operation, and are putting up more

retorts.

In view of my experience, I deny that weak acids must necessarily be formed in the sugar solutions by the use of Mr. Beanes's process, except under the most careless

Owing to the pressure on our space, we are obliged to omit from this letter a tabular comparison of the published analyses of the guano under discussion, with an analysis of Peruvian guano made in 1856 by Mr. Way.

and unskilful management. Only two circumstances can give rise to the formation of weak acids in connection with the process of Mr. Beanes. Either the bone-black is left acid and the liquor dissolves acid from the boneblack, or the water left in the bone-black weakens the liquor sufficiently to allow fermentation to take place readily.

At the refinery of Messrs. Havemeyers and Elder there is no trouble from either cause of acidity. The sugar solutions after filtration are neutral.

I am led to believe, from the passage of Dr. Wallace's discourse quoted above, that an account of the means we employ to avoid acidity in the bone-black would be of use to the refiners in England who purify their bone-black by Mr. Beanes' process. I may briefly state that acidity is prevented in the bone-black

1. By using peroxide of manganese in the hydrochloric acid generator, to avoid the formation of sulphurous gas. 2. By saturating the bone black with hydrochloric acid gas only when it is dry and very hot, as it comes from the revivifying kilns.

3. By using the hydrochloric acid gas dry. 4. By allowing the saturated bone-black to stand in suitable receivers till the excess of gas, if any, is absorbed before washing.

5. By washing the bone-black thoroughly after saturation to remove the chloride of calcium and other soluble salts.

It may be well to state that the use of wet bone-black in the filters consequent on the employment of the process of Mr. Beanes, is not of itself a cause of acidity in a refinery. On the Continent of Europe, and I believe in England, the bone-black is often used wet in the filters without any harm resulting from this practice. Differences of results obtained from the use of wet black must be due to differences of management.

In the two largest refineries in the United States, that of Messrs. Havemeyers and Elder of New York, and the Franklin Sugar Refinery of Philadephia, also at Las Canas, the Sugar Estate of Don Juan Poey, the scientific planter of the island of Cuba, the process of Mr. Beanes has been adopted, is working successfully, and the best results have been obtained.

Dr. Wallace renders a just tribute to the process of Mr. Beanes when he says that it is "otherwise all that would be desired." I am able to add that it is not necessarily a source of acidity in a refinery.

The apparatus in use at the above-mentioned establishments differs from the one previously in use in the manner of drying the hydrochloric acid gas, which is accomplished without the use of chloride of calcium.

Hoping that the above may prove useful to the sugar refiners of England,-I am, &c.,

98, Wall Street, New York, February 22nd, 1869.

P. CASAMAJOR.

MISCELLANEOUS.

Solubility of Indigo.-M. Camille Koechlin has discovered the curious fact of the solubility of indigo in alkaloid salts, and particularly in the acetates and chlorides of aniline, morphine, &c.

Fearful Explosion.-On Wednesday afternoon a terrible explosion occurred at the works of Messrs. Demuth and Co., the well-known carbolic acid manufacturers. A retort burst, and set fire to a number of barrels of naphtha. Two of the employées were burnt to death, and four others received very serious injuries.

Scientific Instruments.-We understand that Mr. Heisch has relinquished the proprietorship of the business at 69, Jermyn Street, carried on under the name of Murray and Heath. He is succeeded by Mr. Robert Murray, whose father established the business, and as he has for

many years acted as manager for Mr. Heisch, he will, we believe, fully maintain the just reputation this firm has acquired.

Remarkable Property of Teroxide of Thallium.-Chemical processes enable teroxide to be obtained with great facility as a dark brown powder, presenting a striking resemblance to peroxide of lead. All that is necessary for this is to digest by heat some newly precipitated chloride of thallium in a solution of hypochlorite of soda, containing an excess of alkali. If a mixture of this dry teroxide and flour of sulphur is submitted to a moderate friction it ignites with explosion. When, on the contrary, to the same teroxide is added the eighth of its weight of the product vulgarly called golden sulphur, it is observed that the ignition requires less rubbing, and takes place without explosion. We may then hope, sooner or later, for a useful pyrotechnic application of this product. Among other properties, M. Böttger calls attention to that which this mixture possesses of being set on fire by the faintest electric spark, far surpassing in this respect the known mixture of equal parts of chlorate of potash and black sulphuret of antimony. The author observes, by the way, that the picrate of oxide of thallium detonates also very easily under a blow.-Jahresbericht des Physikalischen Vereins in Frankfort, and Dingler's Polytechnisches Journal.—

Chrome Green.-Oxides of chrome are prepared either in the dry or wet way; obtained thus, they vary from greenish grey to a more or less deep greenish yellow. They generally have neither brilliancy nor freshness. It is possible, however, to produce green oxides of chrome which are not devoid of beauty. One of the most intelligent chemists of the commercial world, M. Casthelaz, has, conjointly with M. Leune, prepared a chrome green, which is justly styled imperial green. This colouring matter of a superior brilliancy is obtained exclusively by the wet way. The process consists in slowly precipitating chrome salts by treating them with hydrated metallic oxides, insoluble, or but slightly soluble, in water, or by hydrated metallic carbonates, or hydrated metallic sulphides, or, again, by other salts of weak acids, which easily leave their bases; the action is only produced progressively, and the oxide of chromium is precipitated in the hydrated form; the colour of the compound is magnificent, of a deep emerald green. For this preparation, it is convenient to adopt economical reagents, such as gelatinous alumina, oxide of zinc, carbonate of zinc, sulphide of zinc, &c., whose price is reasonable. The same result may be obtained by treating a chrome salt with the non-alkaline metals, which have a sufficient affinity to unite with the acid of the chrome salt and precipitate the oxide. Iron and zinc will be more particularly used, as they are cheaper. It is necessary to select from among the metals, with their oxides and salts, those which, with the acid of the chrome salt, give soluble salts, as they should be removed by washing. If recourse is had to reagents forming, with the acid of the chrome salt, insoluble salts, it is only in order to modify the colour and composition of the chrome precipitates and of the green colour thus formed. As to the magnificent imperial green colour obtained by M. Casthelaz, it possesses properties which will enable manufacturers ultimately to renounce the justly condemned and dangerous copper and arsenic greens. The use of the imperial green removes all danger from insalubrity; it is an impalpable substance, of perfect tenuity. It is believed that this property will cause the new green to be adopted for printing on stuffs, and for other purposes. The oxides of chrome known up to the present time, and generally obtained in the dry way, cannot, by pulverisation, attain to the degree of fineness of the imperial green. It is expected that this substance will have great success in oil painting, coloured papers, colours, and artificial flowers, printing, lithography, perfumery, and soap manufacture, as well as in the making of glass and in the ceramic arts.-Moniteur Scientifique.

PATENTS.

Communicated by Mr. VAUGHAN, F.C.S., Patent Agent, 54, Chancery Lane, W.C.

GRANTS OF PROVISIONAL PROTECTION FOR SIX

MONTHS.

3965. A. G. Gazalat, Rue Gaillon, Paris, "Improvements in the manufacture of steel, and in the apparatus employed therein."-Petition recorded December 30, 1868.

337. L. Wray, Ramsgate, Kent, "An improved process for carbonising and hardening wrought-iron."-February 3, 1869.

355. F. Braby, Camberwell, Surrey, "Improvements in the treatment and utilisation of the waste solution of sulphate of iron resulting from the cleansing of iron surfaces in the process of galvanising."February 5, 1869.

419. P. Taysen, Leith, Scotland, "Improvements in the manufacture of stearic and oleic acids."-A communication from J. C. A. Bock, Copenhagen, Denmark.-February 10, 1869.

434. H. Edwards, Staple Inn, Holborn, "An improved preserved food."

442. W. E. Newton, Chancery Lane, "Improvements in the manufacture of explosive compounds."-A communication from A. Nobel, Paris.-February 12, 1869.

460. A. H. Lewis, Fenwick Street, Liverpool, "Improvements in extracting copper from its ores."-A communication from T. S. Hunt, Montreal, and J. Douglas, jun., Quebec, Canada. February 15, 1869.

469. L. N. Legras, Wardour Street, Middlesex," Improvements in the preservation and disinfection of animal and other substances, and in the apparatus employed therein."

473. C. E. Brooman, Fleet Street, London, "Improvements in treating the waste of wool, silk, horn, and other nitrogenised animal matters to be used as manure."-A communication from P. Pichelin, Orleans, France.

488. W. R. Lake, Southampton Buildings, Chancery Lane, “An improved method of obtaining benzole and its homologous substances from coal gas."-A communication from H. Caro, A. Clemm, C. Clemm, and F. Engelhorn, Mannheim, Baden.-February 17, 1869.

NOTICES TO PROCEED.

3154. W. E. Gedge, Wellington Street, Strand, "Improvements in the manufacture or preparation of artificial fuel."-A communication from C. de Lin, and A. C. Dalma, Rue Blondel, Paris.-Petition recorded October 15, 1868.

3177. E. T. Hughes, Chancery Lane, "An improved adhesive substance."-A communication from J. Totin and A. Totin, Montreuil, France.-October 17, 1868.

3203. G. Chapman, Glasgow, N.B., "Improvements in treating sewage in order to obtain valuable products therefrom."-October 20, 1868. 3248. J. Baggs, High Holborn, "Improvements in smelting, carburising, and purifying iron."

3250. J. Spratt, High Holborn, "Improved preparations of food for horses, cattle, game, poultry, and other domestic animals, such preparations being capable of admixture with compounds for the production of a medicated food for man."-October 24, 1868.

275. N. C. Szerelmey, Belgrave Road, Pimlico, "Improvements in making tarpaulin in different colours, and in treating sail-cloth and other fabrics to preserve them from rapid destruction by the sea air and other corroding influences."-January 29, 1869.

NOTES AND QUERIES.

Guano of Mexillones contains, according to Bobierre's analyses, 33 per cent of phosphoric acid, equal to 71°5 per cent of tribasic phosphate of lime.

Silicated Hydrogen.-Mr. Freidel has just discovered that this gas is entirely decomposed by the electric spark, giving rise in the eudiometer to a shower of amorphous silicium of a brown colour.

Fibrin of Blood.-According to Messrs. Béchamp and Estor, the substance denominated fibrin of blood is only a kind of membrane formed by the microzymas of the blood associated or accompanied by a substance secreted by them by means of the albumenoid substances of the blood.

Aniline Black.-" New Berne is referred for this matter to the CHEMICAL NEWS, August, 1866, p. 59, and to the volumes of Elsner's Chemisch Technische Mittheilungen, published annually since 1846, all of which may be inspected at the free library of the Commissioners of Patents.

Atomic Weight of Lanthanum.-M. Zschiesche has prepared sulphate of lanthanum of such a purity that a thickness of 17 centimetres of a saturated solution gave no trace of the absorption bands of didymium. Working on this, he has found the atomic weight of lanthanum to be, from a mean of six experiments, 45'09. The extremes were 44'72 and 45'625.-Journ. de Chim. Prat.

Picrate of Quinine has been tried, according to the Revue Maritime et Coloniale, in the French Navy and some French settlements in Asia and Africa where a peculiar kind of ague was prevalent, but it has not been found to answer at all well, as it affects the digestive organs; besides this picric acid, although intensely bitter to the taste, is now considered not to possess any medicinal properties which would render it peculiarly valuable; its internal use tinges the skin yellow.

Action of Aqua Regia on Sulphur.-Mr. Lefort has studied the action of aqua regia upon sulphur and sulphur ores; he finds that at first there is a chloride of sulphur formed by the disengaged chlorine, but soon after this compound is again destroyed by the action of the nitric acid, and chlorine is set free, while sulphuric acid is formed. Lefort finds that the best proportion of the mixed acids most suitable for the rapid oxidation of sulphur is I part of hydrochloric and 3 of nitric acids, precisely the reversed proportion as used for ordinary aqua regia.

Mr. Sorby's Researches on Diamonds.-Mr. Sorby finds that the supposed cavities in diamonds described by Brewster are in reality enclosed crystals, and the conclusion arrived at from the consideration of the whole structure of the diamond is not opposed to its having been formed at high temperature. The crystals enclosed in diamonds are frequently seen to be surrounded by a series of fine radiating cracks, which are proved to have been the result of the contraction suffered by the diamond in solidifying over the enclosed crystal, and this explanation has been artificially verified by examining crystals formed in fused globules of borax glass, cooled slowly, when the same phe

nomena are seen.

Assay of Gold Quartz.-First let the rock containing gold be roasted at a red heat, as is practised with regard to flints intended for pottery ware manufacture; this roasting renders it easy to break the rock afterwards into small pieces. In this state the rock should be placed in a large earthenware (fire-clay) tube fixed in a furnace in a manner similar to the large fire-clay retorts used in the manufacture of gas (double retorts), open at both ends and projecting beyond the furnace on each end; the heat in the interior of the tube should be bright cherry-red. If, under these circumstances, a current of chlorine gas be passed through the retort, the gold contained in the rock will combine at the high temperature with the chlorine, and become volatile therewith, whereas at the place where the heat of the tube or retort is less high, the chloride of gold will become again decomposed and gold deposited.

Will Steam Ignite Combustible Substances?-This curious question is discussed in a recent number of the Scientific American. It is urged that as the heat generated by a hydrocarbon in combination with a combustible fibre will produce combustion, and as a fibrous material saturated with oil will, if exposed to the sun's rays, burst into flame, it follows that a greater degree of heat, whether produced by steam or any other agency, may produce like results. After mentioning the inflammable condition acquired by wood through which a steam pipe has been passed, it is remarked that every engineer of some experience and close observation knows that it is possible to ignite combustible or inflammable substances by the direct impact of steam. Cases are on record where dry wood was ignited by escaping steam, and, as an experiment, oil-saturated cotton waste and dry pine wood have been lighted by the steam from a boiler at a distance of 12 feet, the pressure of the steam being at the time only 95 lbs., and the temperature of the steam, inside the boiler, not at 12 feet distance thereof, 335° F.; the material burst into flame in a few minutes. I witnessed many years ago a case where a quantity of racine, .., madder root not yet ground, took fire simply by being heated up to about 210° F. by means of the waste exhaust steam from a small highpressure steam-engine being made to pass through a series of pipes, above which the racine was placed on an iron grating in a layer some 4 inches in thickness.-Dr. A. A,

Zoological, 4.

Chemical, 8. Arthur Elliott, "On the Determination of Carbon in Cast-Iron." E. T. Chapman, "On Butylic Alcohol."

Aniline Black for Cotton.-"New Berne" enquires in the "Notes and Queries" whether there is an aniline black for cotton. There is an aniline salt used in this district by many calico-printers which, treated with an oxidising paste made on purpose for it, produces a black considered the best out. If your correspondent will apply to S 48, Post Office, Manchester, he can learn all about it.

Constitution."

Quekett Microscopical Club, 8.

SATURDAY, 20th.-Royal Institution, 3. Dr. Odling, "On Hydrogen and its Analogues."

***Owing to press of matter, our answers to correspondents are unavoidably postponed till next week.