150 Scientific Notices — Chemistry. [Feb. 



quantity of magnesia^ together with some potash, or potash and 

 soda. 



It appears, he says, in conclusion, that when we compare the 

 analyses of the different species of Tourmalines, the most essen- 

 tial ingredients are, boracic acid, silica, and alumina, whose 

 relative quantities do not vary much. It appears further, that 

 any alkaline substance, though in no considerable quantity, may 

 be likewise an essential ingredient. The different nature of 

 these alkaline substances may be employed by the chemist, as 

 we have used it, to divide these minerals into different sections. 

 But it will appear to be quite useless to attempt to give mineral- 

 ogical fovmulaj for the chemical composition of these minerals, 

 when it is considered ; firit, that we can by no means rely upon 

 the correctness of any statement regarding the quantity of oxy- 

 gen in boracic acid ; secondly, that the quantity of alkaline 

 bases, whose oxygen would be unity, is so small, that it cannot 

 be determined (with sufhcient accuracy) without great errors in 

 the computation of the relative quantity of oxygen in the other 

 ingredients; thirdly, that in one species no account could be 

 given of a considerable loss of weight. He has, however, cal- 

 culated the quantities of oxygen in every species, with the inten- 

 tion of comparing the sum of the oxygen contained in the bases 

 wilh the sum of that contained in the acids, viz. boracic acid 

 and silica. The result of this calculation is then fully stated. 



Article XII. 



SCIENTIFIC NOTICES. 



Chemistry. 

 1 . Analysis of the Boletus Sidphureus. 



This mushroom, according to Peschier's analysis, is com- 

 posed of the following ingredients : — 



Water, 



Fungin, 



Albumen, 



An uncrystallizable saccharine matter — mushroom sugar, 



A fatty substance soluble in alcohol, 



An animal matter, 



A peculiar alkaline principle, 



Oxalate of potash. 



An uncombined acid of a pecuhar nature, and 



A colouring matter. 



The uncombined acid and the colouring matter were soluble 

 both in water and in alcohol. — (Trommsdorft's Neues Journal 

 der. Pharniacie.) 



