Water not a non-elastic Fluid. — Boracic Add. — Alkalies. 149 



usually employed for the cure of several diseases of the human 

 body; and what means should be taken, in order to acf|uire a 

 solid knowledge, useful in medicine, of the hitherto unknown 

 chemical agency of several medicines ?" The Essays to be sent 

 to the Secretary before the 1st January 1S21. 



XXV. Intelligence and Miscellaneous Articles. 



WATER NOT A NON-ELASTIC FLUID. 



IvIr. Perkins, the inventor of the curious and useful art of 

 siderography, or of multiplying engravings, (by executing them 

 on soft steel plates, which when hardened are employed to trans- 

 fer the lines in relief, to steel rollers, which rollers are again used 

 to impress other steel or copper-plates with all the lines of the 

 first engraving) has ascertained and proved by actual experiment, 

 that water subjected to a pressure of 326 atmospheres is dimi- 

 nished about I -29th in bulk, ox 3\ per cent. 



BORACIC ACID. 



By experiments made by Dr. Pleischl, of Prague, on crystal- 

 lized boracic acid, it appears to be a compound of pure anhydrous 

 acid 54, water 45 = 99. Experiments made by this chemist on 

 anhydrous boracic acid confirm those of Gay Lussac and Tbe- 

 nard. It is not able to decompose fused chloride of barium — no 

 decomposition or chemical combination was obtained. 



VEGETABLE ALKALIES. 



The number of these is daily increasing, and chiefly by the la- 

 bours of the German chemists. Delphia, Daturia, Hyoscyama, 

 and Atrnpia, were discovered by Dr. Brandes. 



Alropia is the ingredient which gives to the Atropa lelladonna 

 its peculiar properties. It crystallizes in long needles, is a bril- 

 liant white, tastless, and little soluble in water and in alcohol ; 

 withstands a moderate heat ; and forms regular salts with acids, 

 neutralizing a considerable portion of acid. Sulphate of atropia 

 contains sulphuric acid 3fi-52, atropia 38-93, water 24-55 = 

 100. Atropia mixed with potash and exposed to a red heat 

 yields ashes, which when mixed with muriate of iron strike a 

 lively red colour. 



Hyoscyama (the alkali extracted from the Hyoscyamus niger) 

 19 not easily altered by heat, even when brought to redness with 

 charcoal. It crystallizes in long prisms ; and gives with sul- 

 phuric or with nitric acid very characteristic salts. 



Great care and circumspection should be employed in ex- 

 amining 



