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ing blue ; a varnish for labels and artists’ designs, black-ing and French waterproof varnishes.
The specimens of the larger chemical products exhibitedfrom the British manufactories, were frequently on amagnificent scale, and of singular beauty; such as thecrystallized citric and tartaric acids, the chromates andprussiates of potash, sal ammoniac, alum, carbonate andbicarbonate of soda, and the sulphates of copper and iron.The pharmaceutical collections were also remarkably fineand extensive, including very beautiful preparations ofiodine, of mercury, lead, zinc, antimony, silver, potash,and soda; double salts of iron; the salts of morphia,strychnia, and even the rare creatine and creatinine;while medicinal plants were so well preserved as toappear with all the beauty of the living plant. Severalof the processes, also, were illustrated by instructiveseries of specimens, exhibiting the successive steps ofthe manufacture; as the alum process by shales iudifferent stages of decomposition; the different steps intire white lead manufacture; and others. Many finespecimens were also contained in the foreign collections,although generally smaller and less prominent. It wasevident that chemical manufacturing had attained moresubdivision in England than abroad, with larger indi-vidual production. On the other hand, the great varietyof products from a single manufactory was often verystriking in the foreign, particularly the German, col-lections ; a variety without inferiority of quality, whichbore testimony to the excellent chemical education andvaried resources of the exhibitors.
A great reduction in the cost of production is quite asremarkable in chemical substances as in the products ofmechanical ingenuity, and equally indicates improvementin the chemical as in the mechanical arts. The greatstaple articles, such as the mineral acids and the alkalinesalts, have become available, from their cheapness, to avariety of new applications, which are gradually alteringthe aspect of chemical manufactures. Thus we now findsulphuric acid applied directly to clay to form a sulphateof alumina, which competes with alum; and the sulphateof copper, the sulphate of magnesia, and even the sul-phate of iron, produced by the direct combination oftheir constituents. The ore of lead we see treated withthe hydrochloric acid of the soda process to form a rivalpigment to white lead; and the ores of copper and tinfused with alkaline salts, as the means of purification andreduction, or to form a new salt.
Of a large proportion of the chemical products ex-hibited, the features which claimed most of the considera-tion of the Jury were the superior quality aud beauty ofcrystallization of the salts, indicating a high degree ofpurity in their composition, and superior excellence ofmanufacture. Such may be said to be the general groundof the award of the honorary distinctions which have tohe reported. But in a considerable number of instancesthe product was further recommended by its novelty, orby some important improvement in its preparation,which demands more special notice.
Red on Allotropic Phosphorus.
Iodine.
Perhaps the earliest, as they are still among the most es-teemed, manufacturers of iodine on the Continent , after itsfirst discoverer, M. Courtois, are the Messrs. Couhnkkikand Co., of Cherbourg (462, p. 1200), who have created intheir own sphere a branch of industry in the preparation ofiodine, of chloride of potassium, and the other salts of kelp;of which specimens were exhibited, remarkable for purityand beauty. With the exception of the iodine used inphotography, the whole iodine produced appears to bestill consumed in medicine, and chiefly in the form ofiodide of potassium, and other iodides, only a compara-tively small quantity being retained as iodine. Of iodinefrom kelp there are also two Scotch and two Irish Ex-hibitors, who are eacli considerable manufacturers. Thegreat increase in the production of iodine took placeabout 1840. The make of a single house in Scotland ,from 1845 to 1850, averaged 276,000 ounces per annum,aud is believed to form fully one-third of the entireproduce of the United Kiugdom during that period.The price of a pure dry article for the three years,1848, 1849, 1850, remained between ~\d. and S$fl.The price for 1851 is from 6i/. to with an excessof production.
SULPHURET OF CARBON.
Among the newest of chemical manufactures is that ofsulphuret of carbon, represented by Dr. L. C. Marquart,of Prussia (I.—327, p. 1069). This liquid has found a sin-gular application in electro-plating, the addition of a fewdrops of it to the silver solution causing the metal todeposit bright, a fact which appears to have been inde-pendently discovered by the Messrs. Elkington, and byMr. Lyons, of Birmingham , who both exhibit illustrationsof this application of the substance.
The preparation of boracic acid by Count F. de Lar-dkrel, of Tuscany (35, p. 1294), was rewarded by a CouncilMedal. Although this well-known manufacture is not re-cent, having attained its full development at least ten yearsago, still the bold originality of its first conception, theperseverance and extraordinary resources displayed in itssuccessful establishment, and the value of the productwhich it supplies, will always place the operations ofCount de Larderel among the highest achievements ofthe useful arts, and demanded the most honourable re-cognition at this epoch. The vapour issuing from avolcanic soil is condensed, and the minute proportionof boracic acid which it contains (not exceeding 0*3 percent.) is recovered by evaporation, in a district withoutfuel, by the application of volcanic vapour itself as a| source of heat. The boracic acid thus obtained greatlyexceeds in quantity the old and limited supply of boraxI from the upper districts of British India, and has greatly! extended the use of that salt in the glazes of porcelain,and recently in the making of the most brilliant crvstal,when combined with the oxide of zinc instead of oxide oflead.
Of the elementary aud non-metallic substances, aninstance of singular interest was presented in the allo-tropic phosphorus of Schrotter, manufactured and exhi-bited by Messrs. J. and E. Stcrge, of Birmingham (119,p. 199). The extraordinary conversion of phosphorus intoa red infusible powder is effected by exposing melted phos-phorus in a close vessel, to a degree of heat which is nearthe boiling point of that substance, and which is kept upfor a considerable time. It is probable, from the entirelyinodorous character of the specimens recently manufac-tured, that the amorphous phosphorus is now made with-out the use of sulphuret of carbon to remove any excessof unaltered phosphorus. This new preparation presentsgreat facilities in the manufacture of matches, from beingno longer spontaneously inflammable, aud yielding nosmoke of phosphorous acid; which was found highly in-jurious to health, producing caries of the bones, particu-larly of the lower jaw, iu workmen exposed to it. Thecombination of red lead with the amorphous phosphorusin the matches causes them to ignite as usual by friction.
The most novel feature in the manufacture of sulphuricacid, illustrated in the Exhibition, was the process ofmaking this acid in vessels of earthenware instead of theleaden chamber, as designed by M. Fouche-Lkpklletier(1229, p. 1236), and followed to a large extent at the cele-brated works of Javel, near Paris . The material ot thesevessels is the salt-glaze ware, which resists acids; aud theyare in the form of large Wolfe’s bottles, connected togetherin series. The acid fumes are carried through a largenumber of these vessels, by which the power of con-densation is found to be one-third greater than couldbe obtained from a single chamber of equal capacity ;while their original cost of construction is, to that of aleaden chamber, in the proportion of 12 to 100, and thecost of maintaining them is nothing. Such vessels havebeen in use at Javel since 1846; and of the large annualproduction of 3,600,000 kilogrammes of concentratedsulphuric acid in that establishment, one-third is at