50 ON THE LIME IN CREAM OF TARTAR. 



Cream of tartar, No. 1 



From 2-3 to These different precipitates, which varied from two and 



3 5 percent, ^Xf to t ^ ree an( i j 1;i jf p er cen t, were composed of almost 



pure tartrite of lime, soluble, as Mr. Destouches observed, 



More left in ' jn about six hundred parts of boiling water. T.*he solution* 



solution. of the six sortg of Roc]ielle 8a j t formed, being too dilute for 



crystallization, were left to stand for six days. They afji 



forded fresh quantities of tartrite of lime, which we. did not 



weigh, because the supernatant liquors still afforded a very 



sensible precipitate with oxalate of ammonia. 



A larger pro- 2. A similar quantity of the cream of tartar No. 6, which 



portion obtain* j^ afforded the least portion of tartrite of lime in the pre- 

 ed by cold so- . r . . * 



lution. ceding experiment, was triturated cold with an excess or 



carbonate of soda and a little water. Being afterward di- 

 luted with a sufficient quantity of water to dissolve all the 

 Rochelle salt formed, it left a residuum of a pulverulent, 

 insipid matter, a little yellowish, which, when washed and 

 dried, weighed four drachms and twenty grains. The so- 

 lution of Rochelle salt formed in this operation was still 

 precipitable by oxalate of ammonia, eveu after five or six 

 days. 

 Tartarised na- 3. A pound of distilled water, boiled with four ounces of 



rron took up j^ oc j ie u e 8H | t aiJf ] a drachm of calcareous tartrite, dissolved 

 *ovne in boil- 

 ing, about twenty grains of the latter, the greater part of which 



crystallized on cooling; but the liquor examined at the ex- 

 piration of six days still afforded unequivocal signs of the 

 presence of a salt with a calcareous basis. 

 Vfr. De^tou- This very great difference between our results and those 

 ehes deceived. annouuce d by Mr. Destouches, the much greater proportion 

 of tartrite of lime which we obtained, and the presence of 

 this salt in the solutions and mother waters, clearly pointed 

 out to us, that, deceived by appearances, he did not carry 

 his researches far enough. 

 Analysed dif- Jn consequence, without regarding the preparation of Ro- 

 fereruly. chelle salt, and to find precisely the quantity of tartrite of 



lime contained in the specimens of cream of tartar we had 



tried, 



