1824.] Scientific Notices — Chemistry. 309 



7. Oxalate of Lime decomposed by Potash. 



M. Laugier observed a remarkable fact, which occurred in 

 analyzing an urinary calculus, that the oxalate of lime was com- 

 pletely decomposed by potash. 



" I heated," he says, " 10 parts of the calculus with a weak 

 solution cf caustic potash, with the intention of separating the 

 oxalate of lime from the uric acid, whether free or combined ; a 

 process recommended by all the authors for that purpose. 



" The insoluble portion, which I considered as oxalate of lime, 

 was found to be carbonate of lime without any admixture. As 

 the lime could only be derived from the oxalate with that base, 

 it follows that that salt must have been decomposed by the 

 potash ; and I actually found the oxalic acid, which it had taken 

 from the lime, in combination with the alkali. Desirous of 

 verifying the fact, I took 100 parts of artificial oxalate of lime, 

 and boiled it with a solution of potash, and succeeded twice in 

 decomposing it entirely. I repeated the experiment with 20 

 parts of oxalate of lime detached from a mulberry calculus, 

 harder than ivory, and by two boilings in the alkaline solution 

 completely effected their decomposition. We must, therefore, 

 conclude, that a solution of potash cannot be a proper agent, 

 particularly if heat be employed, for separating oxalate of lime 

 from substances soluble in that alkali, which almost always con- 

 tains carbonic acid, or absorbs it during the operation." — (Jour, 

 de Pharm.) 



Note by the Editor of the Aruiales de Chimie. — The fact 

 observed by M. Laugier entirely changes its character if we 

 suppose the potash employed by that able chemist to have been 

 slightly carbonated, for it is very certain that oxalate of lime is 

 easily decomposed by carbonate of potash. We will ask, there- 

 fore, if perfectly pure potash be capable of decomposing oxalate 

 of lime either wholly or partially? — (Annales de Chimie.) 



8. Analysis of Pinite, from St. Pardoux, in Auvergne. 



Dr. Gmelin's analysis of this mineral gives its composition as 

 follows : 



Silica 55-964 



Alumina (with traces of lime) 25-480 



Potash 7-894 



Soda 0-386 



Oxide of iron 5'512 



Magnesia, with oxide of manganese 3-760 



Water with an animal matter 1*410 



100-406 

 Fluoric acid was sought for, but not found. The preceding 



