394 Scientific Intelligence. [May, 



IV. Detonating Silver and Mercury. 



Dr. Liebig has analyzed both these compounds, prepared by the 

 well-known process of causing alcohol to act upon the nitrates of the 

 respective metals. It appears from the experiments detailed that the 

 substance combined with the metallic bases is an acid, and separable 

 from them by means of the alkalies and metals, and they then form 

 the detonating compounds. To analyze detonating silver and mer- 

 cury, 100 parts of each were mixed with 400 parts of calcined magne- 

 sia, and heated in a retort, the products received were : 



From detonating silver. From detonating mercury. 



Carbonic acid 35 5 25*8 



Ammonia 13-7 10 



Water 7-2 52 



Silver 41-0 Mercury 569 



Loss 2-6 21 



1000 1000 



The above are the mean of four experiments ; these give as the ul- 

 timate elements. 



Detonating silver. Detonating mercury. 



Oxygen 3222 2339 



Hydrogen 322 2-34 



Azote 11-2S 8-23 



Carbon 9 68 7*04 



Silver 41'00 Mercury 56-90 



The salts formed of the acid of these detonating compounds have 

 been termed fulminates. With potash, the salt formed crystallizes in 

 long brilliant plates, which do not affect turmeric paper, have a dis- 

 agreeable metallic taste, and detonate when heated or struck. It 

 consists of 85-08 acid, and 14*92 base. The fulminate of soda crys- 

 tallizes in brown brilliant plates, it is more soluble in water than the 

 fulminate of potash, but resembles it in other properties, and is com- 

 posed of 88*66 acid, and 11-34 of soda. Magnesia, barytes, strontia, 

 zinc, and copper, all combine with this acid to form compounds. — 

 (Ann. de Chim. xxiv. 294.) 



V. Absorption of Air by Mercury. 



In our analysis of Sir H. Davy's paper " On the Electrical Pheno- 

 mena exhibited in vacuo," Annals, N. S. iv. 379, we briefly mentioned 

 his statement respecting the absorption of air by mercury, and its 

 emission when the mercury is heated in vacuo. In Mr. Daniell's Me- 

 teorological Essays, p. 363, we find a different view of the subject ; 

 and as it is one of considerable importance, we now present that view 

 to our readers. 



"• During my experiments upon the filling and boiling of the baro- 

 meter tubes, my attention was particularly directed to the assertion of 

 Sir H. Davy (Phil. Trans. 1822, p. 74), that * there is great reason to 

 believe that air exists in mercury, in the same invisible state as in water, 

 that is, distributed through its pores;' and to the disheartening fact (if 

 proved), that absorption of air 'may explain the difference of the 

 heights of the mercury in different barometers ; and seems to indicate 

 the propriety of re-boiling the mercury in these instruments, after a 



