' 244 An Lwesligalion of the Properties of Lactic Acid. 



with the sulphuric acid. The extract, which is obtained 

 directly from milk, contains tliis salt; but this affords, 

 when mixed with sulphuric acid, a sharp acid smell, not 

 unlike that oi the acetic acid. This however depends not 

 on acetic but on muriatic acid, which in its concentrated 

 state introduces this modification into the smell of almost 

 all organic bodies. The pure lactate of potass is easily so- 

 luble m alcohol ; that which contains an excess of potass, 

 or is still contaminated with the animal matter soluble in 

 alcohol, which is destroyed by the treatment with lime, is 

 slowly soluble, and requires about 14 parts of warm alcohol 

 for its solution. Il is dissolved in boiling alcohol more 

 abundantly than in cold, and separates from it, while il is 

 cooling, in the form of hard drops. 



The lactate of soda resembles that of potass, and can only 

 be distinguished from it by analysis. 



Lactate of ammonia. If concentrated lactic acid is sa- 

 turated with caustic ammonia in excess, the mixture ac- 

 quires a strong volatile smell, not unlike that of the acetate 

 or formiate of ammonia, which however soon ceases. The 

 salt which is left has sometimes a slight tendency to shoot 

 into crystals. It affords a gummy mass, which in the air 

 acquires an excess of acidity. When heated, a great part 

 of the alkali is expelled, and a very acid salt remains, which 

 deliquesces in the air. 



The lactate of baryta may be obtained in the same wav 

 as that of lime ; but it then contains an excess of the base. 

 When evaporated, it affords a gummy mass, soluble in 

 alcohol. A portion remains undissolved, which is a sub- 

 salt, is douiihy, and has a browner colour. That which is 

 dissolved in the -alcohol affxirds by evaporation an almost 

 colourless gummy mass, which hardens into a stiff but not 

 a brittle varnish. It does not show the least tendency to 

 crystallize. The salt which is less soluble in alcohol may 

 be further purified from the animal matter adhering to it, 

 by adding to it more baryta, and then becomes more solu- 

 ble. 



The lactate of lime is obtained in the manner above de- 

 scribed. It aff<irds a gummy mass, which is also divided 

 by alcohol into two portions. The larger portion is solu- 

 ble, and gives a shining varnish inclining to a light yellow 

 colour, which, when slowly dried, cracks all over, and be- 

 comes opake. This is pure lactate of lime. That which 

 is insoluble in alcohol is a powder, with excess of the base; 

 received on a filter, it becomes smooth in the air like gum, 



or 



