\Q ANALYSIS OF CORUNDUM, A>JD O*' 



was little or no appearance of jelly. When the filiea was thus 

 precipitated by evaporation, I filtered the liquor, and boiled it 

 with an excefs of potafh. By this operation, the alumina was 

 precipitated, and then re-diflfolved by the excefs of potafh, from 

 which it was finally obtained by muriate of ammonia ; the iron 

 which had remained undiflblved by the potafh, having of courfe 

 been previoufiy feparated from the alumina. This earth, and 

 the filiea, after being wafhed and dried, were ignited, and thus 

 the weight of both was obtained. 

 Example. Ana- I fhall exemplify, in a fingle inftance, this mode of treat- 

 ies of the fap- ment . an( j then pre f ent ^ re f u it s obtained from the different 

 kinds of corundum. For this purpofe, I fhall felect the blue 

 perfect corundum, or fapphire, as the (tone which has been the 

 mod ably analyzed by Mr. Klaproth. From a view of both 

 analyfes, the etficacy of the fufion with borax will be evident ; 

 and the refuits of the feveral experiments maybe compared. 

 100 grs. fapphire 1. 100 grains of fapphire, pulverized in the agate mortar, 

 were pulverized as al)Qve f(ated had increa f ed to 105. Thefe 105 were mixed 



and then ruled 



into a green glafs with 250 of calcined fub-borate of foda, and put into a platina 

 with 250 borax, cruc i D i e# They were then expofed to a violent heat for two 

 hours, and afterwards allowed to cool. The mafs was vitrified, 

 and had the appearance of a greenifh blue glafs, fiflured in 

 many directions, 

 which was dif- 2. This glafs being ftrongly attached to the platina crucible, 

 folved in boiling ^ e w hc-le was put into muriatic acid, and boiled for fome 

 hours. By thefe means, a total and limpid folution was ob- 

 tained. 

 Precip. by carb. 3. The matter of the ftone was next precipitated, by am- 

 ofammonia,was j a fc entirely faturated with carbonic acid; the liquor 



wafhed, dried, J . . 1 1 . 1 t 



diflblved in mur. was filtered; and the precipitate well wafhed and dried. It 



and expof. to was tnen re diflblved in muriatic acid, and evaporated. 



it V gave a precip. 4. By this evaporation a precipitate was formed, which, 



of 10.25 filiea. w hen well wafhed and ignited, weighed 10,25 grains, and 



was filiea. 



The water of 5. The liquor, together with that which had wafhed the pre- 



wafhing and the c jpjt a te, was boiled in a filver veffel, with an excefs of potafli ; 



mur. liquor were * ,.„ , . „ . . ., , 



boiled with ex- this rediflblved all the precipitate, except one grain. 



cefs of potafh. g t Muriate of ammonia was poured into the alkaline folution. 



£o"n rSn^d. ( No - 5 -) The potafh expelled the ammonia from the muriatic 



Mur. ofamm. acid, and, forming muriate of potafli, could no longer retain 



Zk-. foJution.^ the earth in * olution > a vei 7 co P ious precipitate, therefore, was 



formed. 



