647 
of Edinburgh, Session 1871 - 72 . 
The small quantity of substance left I have employed for the 
purpose of corroborating the production of pyruvic acid, when it is 
treated with hydrate of baryta. 
Took a decigramme of cystine, treated it in a tube with a solu¬ 
tion of hydrate of baryta, and heated it all night to a temperature 
of 130° C., opened it, and transferred contents to a beaker, boiled 
to expel the ammonia produced, then added an exactly equivalent 
quantity of sulphuric acid, filtered from the sulphate of baryta; 
after boiling to expel the sulphuretted hydrogen, the filtrate evapo¬ 
rated contained a yellow syrupy acid, which contained a few crystals 
under the microscope, having the appearance of Finck’s uvitic 
acid. Ammonia w 7 as added, and gave a yellow solution, which was 
evaporated on the water-bath; it was dissolved in water, and gave 
a white precipitate, with nitrate of silver, which was not distinctly 
crystalline ; it also gave a white precipitate with subnitrate of 
mercury, and a red colour with a crystal of sulphate of iron, and 
no precipitate with sulphate of copper. The barium salt was also 
found to be non-crystalline, the acid lost the power of giving a red 
colour with Ferric salts after treatment with sodium amalgam, 
and the composition of the silver salt agreed better with pyruvic 
acid then formerly. 
Considerable progress has been made in an examination of the 
chemical characters and relations of the thio-pyruvic acids. 
Normal thio-pyruvic acid has been obtained from the di-chlorpro- 
pionic ether. When this ether is treated with excess of alcoholic 
sulphide of potassium, we obtain at once a precipitate of chloride 
of potassium, and a solution of the potash salt of the new acid. 
When this is diluted with water, acidulated with sulphuric acid, 
and shaken up with ether, the acid is obtained in yellow crystalline 
plates, part of it seems to remain a viscid fluid. The lead and 
silver salts are white and insoluble, blacken when heated. It pre¬ 
cipitates mercurous salts black from the first. The calcium, barium, 
iron, cadmium, and copper salts are all soluble. The potassium 
and sodium salts are intensely yellow, and decompose slightly on 
exposure to the air. When treated with tin and sulphuric acid, 
they evolve sulphuretted hydrogen. 
The thio-carboxyl pyruvic acid has not yet been obtained in a 
pure state. When pyruvic acid tr eated with pentasulphide of 
phosphorus, a violent action takes place, associated with much 
