ON SACCHARUM LACTIS 207 



of the powder, remained, which at first was not so exactly 

 separable by edulcoration. I now found that this powder 

 was a salt, because it was soluble in water ; ifc was now 

 purified by means of the solution and crystallisation. The 

 properties of this salt are the following : 



SECTION VI. 



Half an ounce of it was dissolved in a glass vessel in 30 

 oz. of boiling water ; and after the solution was cool it was 

 filtered. It had the sourish taste. The tincture of lacmus 

 was reddened by it. It made an effervescence with chalk. 

 2 drms. of this salt were exposed to an open fire in a glass 

 retort, when it immediately melted, grew black, and frothed 

 very much. Into the neck of the retort a brown salt was 

 found sublimed, which smelled like a mixture of the salt of 

 benzoin and salt of amber. 11 grs. of coal remained in the 

 retort. The receiver contained a brown liquid, without any 

 mark of oil ; its smell was like the sublimed salt ; it also 

 contained some of this salt dissolved, which was separated 

 from it by a gentle evaporation. The salt that was sublimed 

 weighed 35 grs., had a sour taste, was easily soluble in 

 spirit of wine, more difficultly in water, and burned in the 

 fire with a flame. Concentrated vitriolic acid exposed to 

 distillation with this salt became black, frothed very much, 

 and decomposed the salt entirely. All these circumstances 

 show that this salt is to be classed among the vegetable 

 acids, under the title of Acid of sugar of milk. 



SECTION VII. ITS EFFECTS UPON ALKALIES. 



I poured depurated acid of sugar of milk, in small 

 quantities at a time, into a hot solution of alkali of tartar, 



