.. not taken CHEMICAL NEWS,} 137 siderable proof of the accuracy of their methods of sam- considered them very satisfactory. It was urged against it pling, the principle of which had always been that the that the manurial produce was not worth much, but here samples should be taken in proportion to the amount of in Glasgow they were able to sell the veriest rubbish of flow at the time. Thus the amount of nitrogen in parts city manure at a good price, and surely there could be no per 100,000 in the sewage had been, according to the cal. difficulty in selling a better quality. From what he had culations from the results of the gauging and analyses, seen of Mr. Coleman's process, and of the A B C process, as follows: he had come clearly to the conclusion that very much 1871–72 could be done by using the cheap charcoal which lay in 5'529 1872-73 such abundance at our doors. But we must get rid of 5'151 1873–74 adopting a general principle to every particular case, and rather consider all the individual circumstances which 1874–75 5'560 1875-76 would make it easy or difficult to deal with the sewage of 5*530 a town. Much might be done too by getting the large The rainfall in 1872-3 was excessive, which accounted for public works to adopt the most available methods. the small proportion of nitrogen, and with regard to 1874.5 Some further discussion followed, in the course of the number given was the result of a single analysis of all which the Lord Provost asked if the Sewage Committee the monthly samples taken in quantities proportionate to would explain how irrigation could be adoped in the case the amounts of sewage distributed each month. Experi- of such a city as Glasgow, where there was a vast popula, ments made with bottled sewage and effluent water (kept tion, and where land in the neighbourhood was scarce and for some time) showed that the total amount of nitrogen / out of level with the town. in the solid matter was not altered by keeping. The Dr. Gilbert replied that no doubt an enormous quan. nitrogen in the effluent water was almost all converted tity of land would be required in the case of Glasgow, but into nitrates. This applied to filled bottles. In the case a mixed system of irrigation and filtration through soil of unfilled bottles, a large quantity of the nitrogen in the might be adopted. sewage was lost, while in the effluent water it was only slightly diminished in amount, but was almost all oxidised to the condition of nitrates. Regarding the produce of the farm, the report stated that three plots of Italian rye. ON A NEW CHEMICAL TEST FOR ALCOHOL. grass yielded respectively 58, 53, and 48 tons per acre. The By EDMUND W. DAVY, A.M., M.D., Professor of Forensic highest average of mangold crops had been nearly 47 tons Medicine, Royal College of Surgeons, Ireland, &c. per acre. The nitrogen recovered in the crops was 20,558 lbs., equivalent to 30*34 per cent of that received in the sewage. Dr. Corfield concluded by stating that the lease Whilst making lately some experiments on molybdic of the farm being now up, and as another field of opera- acid, I observed that when a solution of that substance in tions had not yet been obtained, the committee did not strong sulphuric acid was brought in contact with alcohol, in the meantime ask to be re-appointed. there is very quickly developed a deep azure blue colouraMr. E. C. C. Stanford said he was sorry that the tain) hitherto unrecorded, led me tion; and this fact, being (as far as I was able to ascer to investigate the report of the Sewage Committee had developed very much reaction to determine the cause of this production of into a mere report on irrigation. The committee had colour. done valuable work, no doubt, but they had not treated As I found that the protosulphate of iron, and the protothis subject of sewage in the broad way to which it was entitled, and the result was that no question had been a similar effect on this solution, there was but little doubt chloride of tin, iwo powerful deoxidising salts, produced thoroughly sifted, save that of Mr. Hope's farm. Even in that it was due to the deoxidising action of alcohol on the connection with that the committee had left out what molybdic acid. And I afterwards found that the blue sewage reformers wanted most to know, namely, the substance which was formed in the case of alcohol balance-sheet. Dr. Gilbert said he thought it would be found that, in possessed all the characters of the blue compound which is produced when molybdic acid or its salts are acted on the earlier years of the committee's work, they had in, by different reducing agents, whereby a substance convestigated other processes besides that of irrigation, and sisting of five atoms of the metal molybdenum with fourhad reported upon them, though, for substantial reasons, teen of oxygen is obtained, which is usually regarded as a investigation was not followed up. Mr. Stanford had combination of the binoxide of molybdenum with molybdic lamented the absence of a balance sheet in connection acid, the following formula (MRO2,4M003) representing with the report on Mr. Hope's farm. In reply to that he its composition. was quite free to admit that there had been a loss on the With certain precautions, which I shall presently point working, but his clear opinion was that, loss or not, the out, I have found that this reaction of alcohol on the country ought to resort to irrigation. molybdic solution stated is extremely sensitive, so that by Mr. Spence said it had come to be a question its indications very minute quantities of alcohol, even between precipitation and irrigation, and the latter was when diluted with large proportions of water, may be nearly impracticable in the case of very large towns. readily detected. Thus, for example, if one part by His conviction was that precipitation by sulphates was volume of commercial rectified spirits be mixed with the only true solution. 100 parts of distilled water, and one small drop of this Mr. W. R. W. Smith had no doubt that for large mixture be taken, the minute quantity of spirit contained towns irrigation was simply impossible. Five or six in it can be easily detected by the deep blue colouration years ago, when the Rivers Pollution Commissioners said which will be immediately developed on bringing it into there was nothing for it but to irrigate, he told them he contact with the molybdic solution, employed in the would make the prediction that no man then alive would manner about to be described. But this is not the limit ever see irrigation adopted in Glasgow. He took Dr. of the delicacy of this test, for I have been able by means Chalmers Morton's figures, and calculated from these that of it to detect the spirit in one drop of a mixture of disit would require 20 square miles for the production of tilled water and anhydrous spirit, in which the latter sub. grass, and that it would take all the cattle in the three stance constituted only the one-thousandth part of its counties of Lanark, Renfrew, and Dumbarton to eat volume ; and as the drop was found to weigh 6-10ths of a that grass; or, if they grew other crops, it would require grain, the quantity of real or anhydrous alcohol contained 120 miles of land. Now, where were they to get such a in it would be less than the 1-1666th part of a grain of space of ground for irrigation purposes ? With regard to that substance. Mr. Coleman's paper (CHEMICAL News, vol. xxxiv., p. 125), he had seen that gentleman's experiments and * A paper read before the Royal Irish Academy, 138 CHEMICAL News, { New Chemical Test for Alcohol. Sept. 29, 1876. Though small quantities of spirit, even when consider. | amylic alcohols, those being the only ones I had for my ably diluted with water, will produce with the molybdic experiments. But it is more than probable that some at solution the blue reaction without the assistance of any least of the other alcohols may act in a similar manner; external heat, still, where very minute quantities, diluted | however, the reaction is much more rapid and striking in with such large proportions of water as those just stated, the case of ethylic than in that of any of the otther are to be detected, it is necessary, for the success of the alcohols mentioned. I found also that certain salts of experiment, that the reaction should be assisted by a the radicles of those alcohols produced a somewhat gentle heat, and also that too great a dilution of the test similar reaction, as well as ethylic ether and aldehyd, solution with the liquid under examination should be and also several organic matters which are readily susavoided, as the blue colouration will not be developed if ceptible of oxidation. water be in excess; and even after it has been produced, The circumstance that the reaction described is not the addition of a certain proportion of that substance peculiar to ethylic alcohol will, no doubt, lessen its value quickly causes its disappearance. Such being the case, as a positive test for that substance; but a similar objecthe best way of employing the test, according to my ex- tion appertains to all the other known tests for that comperience, is to place three or four drops of the molybdic pound, as their indications are not peculiar to that solution in a small white porcelain capsule, and having alcohol alone, if we except, perhaps, Berthelot's test, heated them slightly, allow one or two drops of the liquid which is founded on the development of benzoic et her to be examined to glide or fall gently on the acid solution, by the action of benzoic chloride, along with caustic when there will be developed, either immediately or after potash on ethylic alcohol. But, owing to the trouble a few moments, the blue colouration. And where the attendant on the preparation of benzoic chloride, and alcohol is very largely diluted with water, it is better to some other practical inconveniences connected with the continue the gentle heating of the test solution for some application of that test, it is not likely that it will ever time, to concentrate it or expel as much water from it as come to be one of very general employment. possible, before adding the liquid to be tested, for, in this The test, however, which I have brought before the way, I have succeeded in detecting the spirit in mixtures Academy has this advantage over those already known, so dilute as to give no blue reaction when added immedi- that it far exceeds (according to my experiments) any one ately to the test solution on its being simply warmed. As of them in point of delicacy. And though the circumregards the application of heat, I must observe that the stance that the blue reaction produced in the case of this temperature of the acid solution must not be raised too test is not peculiar to ethylic spirit lessens, as before high, for if it be heated till the acid evolves its dense observed, its value for the detection of that substance, vapours, or begins to boil, the solution will of itself alone, this is just what renders the test of more general applifrom its partial decomposition, develop a more or less cability; for by its aid certain impurities or adulterations blue colouration, which will become more perceptible on may be at once detected in different substances or comits cooling. But such an occurrence can be easily avoided pounds, which in a state of purity should not contain any by employing a water-bath as the heating agent; for I matter capable of acting on the molybdic solution emhave found that a temperature of 212° F. is incapable of ployed in this test. I may refer to two important subso acting on the test solution-at least an exposure of stances as examples, viz., chloroform and chloral hydrate, several hours' duration to that heat failed to produce the which are now so extensively employed in medicine and slightest blue colouration, and a much lower temperature surgery for a number of useful purposes ; and being agents than that suffices for the application of the test. of great power, it is of much importance that they I should here state that the molybdic or test solution should be free from the accidental impurities of imperwhich I have generally employed was made by dissolving fect preparation, as well as from the frauds of intentional at a gentle heat i part by weight of molybdic acid in adulteration, which may either impair their therapeutic 10 parts of strong and pure sulphuric acid, but the exact value, or even increase the danger of their administration. strength of this solution as regards the amount of molybdic For there can be but little doubt that in some instances acid it contains seems to be immaterial. the serious and even fatal effects resulting from their use I may observe that the colouration produced in the may, in part at least, have been attributable to the imreaction stated disappears after a variable interval of purities or adulterations of the chloroform, or of the exposure to the air-a circumstance which is due, as I chloral hydrate employed. Now, as I find that neither have ascertained, to the absorption of moisture from the chloroform nor chloral hydrate, in their pure condition, atmosphere, and not to the re-oxidation of the molybdenum have any apparent action on the molybdic test, but that compound, as might have been supposed; for amongst many of their usual impurities develop the blue reaction, other facts in proof of this, I may state that after it has it affords us a ready means of testing their purity. Thus, thus disappeared, it may be readily restored either by as regards chloroform, one of its common impurities is expelling the water so absorbed by a gentle heat, or, more ethylic alcohol, which it may contain either from imperslowly, by placing the mixture under a desiccator, and fect preparation, or from fraudulent addition, the very thus removing it by spontaneous evaporation at the high price of chloroform offering a great temptation to ordinary temperature. Such being the case, it is evident the unscrupulous vendor to increase its bulk or weight that, where the test solution has been too much diluted by the addition of alcohol, which so readily mixes with for the immediate development of the colouration de- it. I have found that the molybdic test at once enables scribed, expelling the excess of water by heating the us to detect such an adulteration, even where it occurs mixture on a water-bath, it may be made to exhibit itself. in very small proportions in chloroform. Thus, in one But the necessity for such evaporation should, if pos- experiment, I mixed I part of rectified spirit with sible, be avoided, which, in most cases, will be so by 100 parts by volume of pure chloroform, and one drop of using only a drop or two of the liquid under examination, this mixture being brought in contact with three or four and by employing the strongest sulphuric acid in making drops of the molybdic solution, previously warmed in a the test solution; for it is very probable that much of the water-bath, gave an immediate deep blue colouration spirit contained in the liquid would be lost during its from the spirit contained in it; and, in a second experievaporation in the water-bath ; besides, there would be ment, with a mixture of 1 part of spirit to 1000 parts of some risk that the indications of the test might be more chloroform, a single drop of the mixture, being similarly or less interfered with from particles of dust or organic treated, developed a faint blue reaction. Indeed, so matter getting into the mixture during that process. searching is this test as regards the purity of chloroform, The reaction which has been described, I should state, that I was unable to obtain any sample of that substance in is not peculiar to ordinary or ethylic alcohol, but is more commerce sufficiently pure not to give a blue reaction with or less readily developed by others—at least I found it the molybdic test, owing to the minute quantities of to be so in the case of methylic, propylic, butylic, and volatile oils, and other impurities, they contain ; and for ON THE Sept. 29, 1876. 139 my experiments I was obliged to re-purify the com- the sp. gr. 1.28 and allowed to crystallise. The liquid mercially pure chloroform to obtain a sample which drawn off from the first crop of crystals is further evapo. would give no coloured reaction with my test. rated down to 1'35, when a second smaller quantity of In the case of chloral hydrate, it is stated that one of its chlorate of potash is obtained. A portion, about 12 per usual impurities is the chloral alcoholate (a compound in cent, of the chlorate of potash remains in the motherwhich alcohol, instead of water, is combined with liquor, which can therefore be treated as a source of anhydrous chloral), and that this substance has somewhat chlorine. The crystals obtained are still contaminated different effects on the system from those produced by the with chloride of potassium and iron. To remove these hydrate. This compound, owing to the alcohol it con- impurities the crude salt is dissolved in the smallest postains, gives the blue reaction with the molybdic test, and sible quantity of hot water, 2'5 kilos. of soda are added to I have found that where the chloral hydrate contained 10 hectolitres of the solution, and after the carbonate of even so small a proportion of the alcoholate as i part in lime and oxide of iron have been deposited it is allowed 1000 parts, a little of such a sample being taken indicated to crystallise. The crystals are dried in drying-rooms; the its presence when examined by the molybdic test; and it larger ones are sold without further treatment, and the is probable that some of the other impurities which are smaller ones are ground between rollers. This process, met with in this important substance may be similarly in spite of every care, is sometimes attended with explodetected. sions. Lunge therefore recommends to crystallise the Those two examples are sufficient to indicate the use to salt with constant agitation, and thus obtain it as a cryswhich this test may be applied in the determination of the talline powder. In this manner the purification might purity of different substances used in medicine, as well as also be more readily effected, as easily-soluble salts could in scientific research. be removed from the crystalline powder by merely washFinally, I would remark that, as the reaction of mo-ing with water. lybdic acid on ethylic alcohol is so sensitive and prompt Whilst considerable quantities of chlorate of potash are in its action, I entertain the hope that there may yet be manufactured in England this branch seems to be scarcely founded on it, not merely this qualitative test, but likewise remunerative in Germany, where the same method of a means for the quantitative determination of that im- preparation is adopted. Several establishments have portant alcohol. recently abandoned the manufacture. According to the experiments of F. Hobrecker, 100 parts of chlorate of potash require — 44310 hydrochloric acid (20° B.); REPORT 7720 manganese (65 per cent); 418.0 lime; 72:7 chloride of potassium (92 per cent; 2262'0 lignite. Bromine.-However considerably the production of DEVELOPMENT OF THE CHEMICAL ARTS bromine had increased in the earlier decennial periods of DURING THE LAST TEN YEARS.* its manufacture on the large scale, and however easily vast quantities of this body could be made available for By Dr. A. W. HOFMANN. the arts, its industrial applications, and consequently its (Continued from p. 118.) production, have increased very little in the last few years. Whilst formerly the raw material for its prepara tion was derived from the mother-liquors of salt springs Chlorine, Bromine, Iodine, and Fluorine. By Dr. E. MYLIUS, of Ludwigshafen. and from sea-water, especially that of the Dead Sea, which though richly bromiferous is too remote from the centres Potassium Chlorate.-No important change in the of consumption for chemical products, a new source has manufacture of the chlorate of potash has been introduced been discovered in the mother-liquors of the clearing salts in the last few years. Now, as well as formerly, it is (Abraum salz) of Stassfurt, which can be easily adapted everywhere made according to Liebig's original process, to the demand. In spite of the quantity of bromine which hot milk of lime being saturated with chlorine, and the can be obtained at Stassfurt it is merely a by-product of calcium chlorate, formed simultaneously, with calcium the potash trade, as, in consequence of the small demand chloride, being decomposed by potassium chloride. and low commercial value, the cost of production falls In England, which produces the bulk of the chlorate of little short of the market price. The utilisation of the potash of commerce, it is at present, according to Lunge, Stassfurt "abraum” salts as a source of bromine dates obtained in the following manner.f from the year 1865, when A. Frank introduced this branch For saturating the milk of lime are employed two iron of industry in order the better to compete with the potash cylinders, lined with lead, connected with each other, and from kelp and from salt-springs, and also in the hope of fitted with agitators. These cylinders communicate with superseding the use of iodine in the manufacture of each other, and with the chlorine still by means of tubes, colours. and in such a manner that the contents of the one ap (To be continued). proach the state of complete saturation, whilst in the other any chlorine which may have escaped absorption is taken up by fresh milk of lime. As soon as perfect saturation has been attained in the first receiver, its contents are replaced by fresh milk of lime, and the current of PREPARATION OF SOME COLOURED FIRES chlorine is turned so that it may first enter the second (BENGAL LIGHTS) USED IN PYROTECHNY. apparatus. The solution of chloride and chlorate of calcium thus obtained has a rose-red colour, due, accord By SERGIUS KERN, St. Petersburg. ing to some authorities, to permanganic acid ; but which, according to others (Crace-Calvert), appears also in the In preparing coloured fires for fireworks by means of the absence of manganese. In fact, this rose colour of the usual formulæ given in many manuals of pyrotechny it is liquid is observed also as a sign of the complete satura often very necessary to know the quickness of burning of tion of the liquid where the chlorine employed is obtained coloured fires, so as in some cases, as decorations and without the use of manganese as at Kunheim's works at lances, they must burn slowly, in other cases, as wheels, Berlin, where chlorine obtained by Deacon's process is stars for rockets, and Roman candles, they must burn used in the preparation of chlorate. The red liquid after quicker. Working for some months with many compo, clearing with chloride of potassium is evaporated down to sitions of such kind, I prepared three tables of coloured * " Berichte über die Entwickelung der Chemischen Industrie higher number burns quicker than a fire with a lower fires (red, green, and violet), where every formula with a Während des Letzten Jahrzehends." + Lunge, Dingl. Pol. Journ,, cxxcix., 489. number. For instance, No. 5 burns quicker than No. 6 5 ON THE Per cent. 29 48 21 22 22 22 21 21 12 10. II. 12. II 21 21 21 21 8 No. Per cent. 1. 2. 2 46 51 20 2 140 CHEMICAL NEW Preliminary Note on Litmus. { Sept. 29, 1876. and slower than No. 4. These tables will, I think, be obtained by evaporating the violet-red mother-liquor; it of much assistance in the preparation of fireworks. is a beautiful red, or, from many varieties, green, Huores cent substance, indifferent to acids. The litmus residue Green-coloured Fires. lest after the above treatment with alcohol, and which is Potassium Barium Sulphur. insoluble in that fluid, is digested with distilled water for No. Chlorate. Nitrate. twenty-four hours, after which the deep-coloured solution Per cent. Per cent. is evaporated to dryness on the water-bath, the residuary 36 40 24 extract treated several times with absolute alcohol con23 taining a little glacial acetic acid and again evaporated, 24 53 23 until it forms a brown powdery mass. This brown 57 powder is now extracted with absolute alcohol and acetic 18 60 acid, whereby a large quantity of a scarlet-red body is 16 62 dissolved, which resembles orceine and becomes purple14 64 red, in place of blue, with ammonia. The portion of the 8. 13 66 brown powder insoluble in the acidified absolute alcohol 9. 67 consists of the litmus colouring matter in a state of great 68 purity-so pure, in fact, that by means of it the carbonated 69 alkaline earths contained in spring waters may be titrated 9:5 69:5 with as great delicacy as by the use of cochineal tin&ure, 13. 9 which is far from being the case with crude litmus. To get this perfeály pure, it is first washed with ab. solute alcohol, then dissolved in a small quantity of water Red-coloured Fires. and thrown into a large excess of alcohol; the flocculent purple precipitate collected and again thoroughly washed Potassium Strontium Sulphur. Carbon Chlorate. Nitrate, Powder. with alcohol. I have repeated Wartha's experiments as here stated upon some samples of litmus obtained from Bullock and 32 19 Crenshaw, of Philadelphia, and said to have come from 3 27 Pettiti, Aimee, and Co., Paris, France. My observations 4 23 55 confirm h's results in every particular, save as regards the 5 20-5 I'5 indigo. No deposit of indigo was obtained upon boiling 18 бо the alcoholic tincture, not even aster repeated ebullitions, 7 16 616 with intervals of rest and cooling. 8. 15 The fluorescent body which he mentions is violet or 9. 13 purple, as I have obtained it, and gives a solution in al cohol of a similar colour, which shows a beautiful green 66 fluorescence with sunlight, even when very dilute, and 67 with the spectroscope gives a very characteristic absorp13. 67.25 0975 tion band in the green, together with an almost total 14. 9'25 075 absorption of the violet end of the spectrum. 15. 9 0:65 It is soluble in water, amylic alcohol, and common ether to some extent, extremely soluble in alcohol, but Violet-coloured Fires. seems to be wholly insoluble in bisulphide of carbon, No. Potassium Calcium Malachite, Sulphur. chloroform, petroleum-naphtha, and oil of turpentine, Chlorate. Carbonate. powdered. imparting neither colour nor fluorescent property to those Per cent. Per cent. liquids. 15 The solutions in amylic alcohol and in ether both ex28 5 hibit a beautiful fluoresence, but the ethereal solution 3 26 7 15 shows the absorption band in the green only very faintly, 4 24 9 15 even when the solution is thoroughly saturated. The 5. 23 15 solubility of the substance in both of these liquids is pro13 15 bably due to the trace of common alcohol, which they 7 14 15 both contain, as found commercially. The body which 8. 18 15 resembles orceine shows a very faint fluorescence, and in 9. 16 15 alcoholic solution gives a spectrum in which the absorp10. 15 15 tion is characteristic, and quite distinct from that of the last. It is slightly soluble in water, very soluble in 51 23 15 alcohol, but seems to be insoluble in ether, chloroform, 13. 24 bisulphide of carbon, and petroleum-naphtha. 14. 26 The puie colouring matter proper of litmus is insoluble 15. 51 28 petroleum-naphtha, both in the cold and upon boiling; it an absorption spectrum differing from that of each of the PRELIMINARY NOTE ON LITMUS.* preceding substances. By HOWARD W. MITCHELL. This substance turns blue with ammonia, and seems more like the azolitmine of Kane than either of the other substances, but I obtained no ammonia from it by heating Warthat has separated four organic bodies from litmus. with sodic or calcic hydrates, that is, sufficient to show The first is obtained by treating commercial litmus with its presence by odour or by reaction upon reddened alcohol of about 30 per cent, filtering cold, and boiling the litmus paper. clear tincture; whereupon indigo is precipitated as a fine It yields in alkaline solution a beautiful violet lake with powder, according to the author. The second body is alumina, one of a pale violet colour with stannous acetate, * Read before the American Chemical Society, June 1, 1876. and deep blue lakes with calcium and barium. + Ueber den Lakmussarbstoff. V. Wartha, Ber. Chem. Ges. The residue lest, after extracting litmus with alcoh Berlin, 9, 217. and then with water, is soluble to the extent of 81 10. II. 12. 12 10 I CHEMICAL NEWS, 141 Sept. 29, 1876. cent in dilute hydrochloric acid, and the portion dissolved AN IMPROVED FORM OF ASPIRATOR. in this liquid consists of calcic and magnesic carbonates, free from colouring matter, in the proportions of about By R. H. RICHARDS. 90 per cent and ro per cent of the carbonates respectively. The residue, insoluble in dilute hydrochloric acid, consists The arrangement of this improved form of aspirator is mostly of fine sand, but yields some colouring matter to shown in the figure. strong ammonic hydrate, and forms a solution of a blue colour, with a precipitate, red and gelatinous, somewhat Hydrant water like alumina, upon supersaturation with an acid. About 25 grs. of the pure colouring matter, 15 grs. of the body like orceine, and 10 grs. of the fluorescent body, were obtained per ounce of litmus. Diagrams of the absorption spectra yielded by these several substances I reserve for a second paper.-- American Chemist. Airby v Suction NOTES ON MINERAL ANALYSES. By W. M. HUTCHINGS. The accompanying analyses of chrysocolla and copperpitchblende (Kupferpecherz) may prove of interest to some of the mineralogical readers of the Chemical News. The minerals are from Mexico and are imported into England in considerable quantity for copper smelting. The specimens analysed were very pure and homogeneous pieces, sought out from among a large quantity of freshly broken lumps of ore. The two minerals occur so thoroughly intermixed that it is difficult to find a piece of any size of either of them free from the other; so that it was necessary to break up the best pieces into fragments, picking out with forceps those which were perfeâly pure of either kind. The chrysocolla is light bluish green in colour; hardness, 4'0. The copper-pitchblende is dark brown--almost black-with hardness 6.0. Large amounts of gypsum and clay occur with this ore. Copper carbonates are only present in small quantity here and there. When large lumps are broken open they often show drusy cavities in which the chrysocolla occurs botryoidal. This botryoidal chrysocolla is always coated over with a thin layer of quartz--sometimes amorphous, but more usually beautifully crystallised in very minute crystals. The powdered minerals were dried at 95° C. for some hours previous to analysis. Analysis of Chrysocolla. 25.69 0'26 0*34 Lime 0-74 Magnesia 1:06 Water 6:13 Per cent. A glass tube should be bent of the form represented. This is essential, as it serves to break up the water jet into foam and thus start the suction. I find a hydrant pressure of about 20 pounds on the square inch, equivalent to 40 or 50 feet column of water, will easily exhaust to within i m.m. of the tension of aqueous vapour, and will cause a flask of water to effervesce as the dissolved air is disengaged. .. O'12 NOTICES OF BOOKS. Massachusetts Institute of Technology. President's Re port for the Year ending September, 30, 1875. This establishment continues to be efficiently and successfully conducted. Turning, as a matter of course, to the “ Department of Chemistry," we learn that "in the laboratories for quantitative analysis there has been a large and enthusiastic class," and that “the quality of the work done has, as a rule, been good.” A variety of improvements and additions have been made. Thus "a careful selection of substances, the analysis of which would give an appropriate analytical training for any branch of chemistry, has now been made.” Extra balances have been procured, Bunsen pumps have been replaced by Richard's "jet aspirators," and a modification of the same arrangement is used to supply air to the blast-lamps. The facilities for organic and volumetri: analysis, and for the determination of copper in ores Water :: |