CHEMISTRY. 



95 



woods, and might advantageously take the 

 place of the metallic salts generally employed 

 for that purpose. It is also capable of being 

 very serviceable in painting. The lighter oil 

 for illumination is extracted directly from the 

 wood by submitting it to distillation in spe- 

 cial apparatus, and treating the product with 

 chemical purifying agents. The oil thus pre- 

 pared is of a light yellowish color, and may 

 be used immediately. Belonging to the cate- 

 gory of essential oils and being isomeric with 

 the essence of turpentine, this oil has the same 

 composition (OaoHie), and is distilled at the 

 same temperature, 300 to 340, but has the 

 great advantage over turpentine of not form- 

 ing resin and of not containing pinic or sylvic 

 acid. It is wholly inexplosible, and is there- 

 fore perfectly safe as a light ; and its light is 

 one third brighter than that of petroleum, 

 since it contains 88 per cent of carbon to 82 

 per cent in petroleum. 



Professor Baeyer has communicated a favor- 

 able account of the progress which is making 

 in the manufacture of artificial indigo at Lud- 

 wigshafen, and of the application of the dye to 

 cloth - printing. A cheap cinnamic acid to 

 serve as the base for the preparation is made 

 directly by fusing benzyl chloride with ace- 

 tate of soda, the operation being carried on in 

 large boilers fitted with mechanical stirrers. 

 The cinnamic acid is then treated, by hundred- 

 weights at a time, with nitric acid and the sub- 

 stances required in the successive processes 

 leading to the formation of propiolic acid. The 

 last substance is precipitated from the solution 

 of the soda salt by means of an acid, and, after 

 washing, is sent to market as a paste. Artifi- 

 cial indigo is not itself manufactured at the 

 works, but the coloring-matter is deposited by 

 the printer in the fiber of the cloth from propi- 

 olic acid, as is aniline black from aniline. For 

 this purpose a mixture of propiolic acid and 

 xanthate of soda, to which a proper amount of 

 thickening has been added, is printed on the 

 cloth. The color makes its appearance on 

 exposure to the air. It is found to be fast, and 

 exhibits the characteristic tints of indigo in 

 both light and dark shades. The processes of 

 preparation and conversion, though long, work 

 so well that the whole can be carried out with 

 perfect ease. The only serious imperfection 

 in the series is the loss of 40 per cent of cin- 

 namic acid in the form of para-nitro-cinnam- 

 ic ether. Professor Roscoe suggests that the 

 difficulty arising from this source may possibly 

 receive a solution from the recent researches 

 of Otto Fischer on the synthesis of the rosan- 

 iline dyes by means of para-nitro-benzalde- 

 hyde, a body obtained by the limited oxidation 

 of para-nitro-cinnamic acid. At the time Pro- 

 fessor Baeyer visited the manufactory, 200 

 kilogrammes of propiolic acid paste, contain- 

 ing 25 per cent of the dry acid, were produced 

 every day, and sold at the price of ten shillings 

 per kilogramme. 



M. Pechiney, of the chemical works at Se- 



lindres, France, has made important improve- 

 ments in the manufacture of the chlorates, 

 whereby the loss of from 15 to 25 per cent 

 of the total incurred in the manufacture of 

 chlorate of potash by the ordinary method is 

 reduced to one of below 5 per cent. In the 

 method of preparation heretofore pursued, of 

 treating milk of lime with chlorine and adding 

 potassium chloride to the resulting "crude 

 chlorate liquor," a mixture of two parts of 

 potassium chlorate and about seven parts of 

 calcium chloride is formed, from which it has 

 been impossible to extract more than from 75 

 to 85 per cent of the chlorate of potash in any 

 satisfactory state of purity. In this process 

 the calcium chloride is separated by evaporat- 

 ing to a suitable degree of density, crystalliz- 

 ing by cooling to between 10 and 12 0., add- 

 ing to the mother-liquor water and lime, and 

 heating to determine the formation of oxy- 

 chloride of lime, till only three tenths of an 

 equivalent are left. The solution obtained, 

 after the calcium chloride is separated, can 

 now be made, by adding potassium chloride aa 

 before, to yield 95 per cent of the chlorate of 

 potash in clear crystals. The solution of cal- 

 cium chlorate obtained as above, treated with 

 sodium sulphate, is made to yield chlorate of 

 soda, and this is used with most excellent effect 

 as an oxidizing agent in the process of dyeing 

 aniline-black with the salts of vanadium, for the 

 removal of the surplus aniline and the fixing 

 of the color. M. Pechiney has also introduced 

 a process for recovering sulphur from soda 

 waste by injecting air into the "yellow liq- 

 uor " till the right point of oxidation has been 

 reached, and decomposing with hydrochloric 

 acid. A precipitation of lime takes place dur- 

 ing the process, and this facilitates the opera- 

 tion by rendering a less quantity of the acid 

 necessary. 



ANTISEPTICS. Professor Barff has intro- 

 duced a new antiseptic compound which is 

 adapted to preserve food in a fresh state for 

 any length of time, and appears to be superior 

 to any other application for the purpose. It 

 is called boro-glyceride, and is obtained by 

 heating together boracic acid and glycerine in 

 the proportion of 62 parts of the former sub- 

 stance to 92 of the latter, when it is produced 

 as a hard, ice-like substance. For use it is 

 mixed with about fifty times its own weight of 

 water. A gallon of the mixture, which costs 

 less than an English shilling, will preserve as 

 much meat as can be surrounded by it in any 

 containing vessel. It can be used by untrained 

 persons, and the same liquid may be employed 

 over and over again. The quality of the work 

 of this preservative was proved before the 

 Society of Arts by the exhibition of articles 

 that had been kept in it for several months, 

 and were still perfectly fresh and retained 

 their distinct natural flavors. Its innocuous- 

 ness is proved by the fact that milk treated 

 with it was used at a college near London, 

 containing three hundred persons, during all 



