Chemical Science, 409 



milk or meat is to be dissolved in strong alcohol and mixed with a strong 

 alcoholic solution of tartaric acid, whilst any precipitate falls : being 

 left for twenty-four hours in a cold place, the double tartrate separates. 

 The solution being evaporated, the extract is to be dissolved in water, 

 and well pulverised carbonate of lead added as long as it dissolves, 

 and till the solution has a sweet taste ; it is then to be acted upon by 

 animal charcoal, and afterwards by sulphuretted hydrogen, to remove 

 the lead. The liquid is to be evaporated that all sulphuretted hy- 

 drogen may be expelled ; and then, mixed with hydrated protoxide of 

 tin recently prepared, well washed and still moist, it is to be left 

 several days in contact, with agitation at intervals. The sublactate 

 of tin produced, when well washed, is to be decomposed by sulphu- 

 retted hydrogen, and thus the purest possible lactic acid has been 

 obtained. In this way much acid remains in the solution and is 

 virtually lost. Whether this is another acid, resulting from the 

 partial decomposition of that under purification, or whether it forms 

 a soluble perlactate of tin, is uncertain : but the liquid from over the 

 protoxide of tin, when acted on by sulphurretted hydrogen, gives bi- 

 sulphuret of tin. 



Another process is to saturate the acid alcoholic extract with carbo- 

 nate of potassa or soda : evaporate and heat the mass obtained in a 

 sand bath till it fuses, becomes brown and evolves the odour of urine, 

 and ultimately of herring, or roast meat : to dissolve in water, act 

 by animal charcoal till colourless ; filter, evaporate to dryness ; dissolve 

 in alcohol ; decompose by tartaric acid ; remove the excess of tartaric 

 acid by carbonate of lead ; precipitate the lead by sulphuretted hy- 

 drogen, and evaporate. In this way colourless acid is obtained, but it 

 contains extractive matter, and is less pure than the former. 



Lactic acid is colourless, inodorous ; it possesses a sharp taste, 

 rapidly diminishing on the addition of water till the taste is nearly 

 lost. When evaporated at 212 F., until it loses nothing more, it 

 becomes thick so as to flow with difficulty or even to be a soft solid. It 

 attracts moisture from the atmosphere. When strongly heated, it 

 becomes brown, boils slightly, evolves a suffocating odour like that of 

 heated oxalic acid, blackens, swells, and leaves a bulky charcoal. It 

 dissolves readily in alcohol and in small quantities in ether. 



Many of the salts are uncrystallizable, or gummy ; those of potassa, 

 ammonia, magnesia, and zinc crystallized. They dissolve in alcohol, 

 though sometimes with difficulty, especially if there be excess of base 

 present*. 



18. ON CAMPHOR AND CAMPHORIC ACID. M. J. Liebeg. 



The accounts given of the camphorates by R. Brandes and Bouillon- 

 Lagrange are extremely different. These differences are, by M. Liebeg, 

 referred to these chemists having used two different kinds of cam- 

 phoric acid. Camphor, acted upon by concentrated nitric acid, 



* Ann, de Chimie, xlvi, 420. 



2 E 2 



