j4n investigation of the Properties of Lactic ^cid. 243 



bf the superfluous lime held in solution was precipitated. 

 A sinall portion of it was then decomposed by oxalic acid, 

 and carbonate of silver was dissolved in the uncombined 

 lactic acid, until it was fully saturated. With the assistance 

 of the lactate of silver thus obtained, a further quantity of 

 muriatic acid was separated from the lactate of lime, which 

 was ihtn decomposed by pure oxalic acid, free from nitric 

 acid, taking care to leave it in such a slate that neither the 

 oxalic acid nor lime water afforded a precipitate. It was 

 then evaporated to dryness, and dissolved again in alcohol, 

 a small portion of oxalate of lime, before retained in union 

 with the acid, now remaining undissolved. The alcohol 

 was evaporated until the mass was no longer fluid while 

 warm ; it became a brown clear transparent acid, which 

 was the lactic acid, free from all substances that we have 

 hitherto had reason to think likely to contaminate it. 



The lactic acid, thus purified, has a brown yellow colour, 

 and a sharp sour tastcj which is much weakened by dilut- 

 ing it w ith water. It is without smell in the cold, but 

 emits, when heated, a sharp sour smell, not unlike that of 

 sublimed oxalic acid. It cannot be made to crystallize, and 

 does not exhibit the slightest appearance of a saline sub- 

 stance, but dries into a thick and smooth varnish, which 

 slowly attracts moisture from the air. It is very easily so- 

 luble in alcohol. Heated in a gold spoon over the flame 

 of a candle, it first boils^ and then its pungent acid smell 

 becomes very manliest, but extremely distinct from that of 

 the acetic acid ; afterwards it is charred, and has an empy- 

 reumatic, but by no means an animal smell. A porous 

 charcoal is left behind, which does not readily burn la 

 ashes. When disiilled, it gives an empyreumaiic oil, wa* 

 tor, empyreunjalic vinegar, carbonic acid, and inflammable 

 ji;ascs, VVith alkalis^ earths, and metallic oxides, it affords 

 |)eculiar salts ; and these are distinguished by being soluble 

 in alcohol, and in general by not having the least disposi- 

 tion to crystallize, but drying into a mass like gum, which 

 slowly becomes moist in the air. 



Lactate of potass is obtained, when the lactate of lime, 

 purified as has been mentioned, is mixed warm with a 

 warm solution of carbonate of potass. It forms in drying 

 a guiinny, light yellow brown, transparent mass, which 

 cannot easily be made hard. If it is mixed with concen- 

 trated sulphuric acid, no smell of acetic acid is perceived; 

 ^ut if the mixture is healed, it acquires a disagreeable pimgent 

 'iiell, which is observable in all amnlal substances mixed 

 Q 2 with 



