OP ARTS AND SCIENCES. 19 



the decim acid, contains only 5.4% of HNO3 ; and hence one gramme 

 of antimony, according to our reaction, ought not to dissolve, if less 

 than 10 cubic centimetres of this decim acid were used. Now, in one 

 experiment, of which we have the details on record, 5 grammes of 

 finely powdered antimony were treated in an open flask with 50 cubic 

 centimeti-es of strong and pure hydrochloric acid, and to this only 1 

 cubic centimetre of the decim acid was added. The flask was placed 

 in a warm place (30° C), and frequently shaken. After a short time, 

 the acid became colored reddish-yellow, and the chemical action began. 

 As soon as it ceased, the materials in the flask were shaken together, 

 when the solution became as colorless as water. But on standing in 

 the air the color rapidly returned, and we observed that it always 

 spread from the surface of the liquid downwards. These phenomena 

 were repeated again and again, until after many days the whole of the 

 antimony dissolved. According to our reaction, the 5 grammes of 

 metal should have required 50 cubic centimetres of acid, so that the 

 effect was obtained with only one-fiftieth of the amount indicated by 

 this theory. The action is probably due to the NO, which remains in 

 solution, and in conjunction with the oxygen of the air decomposes the 

 hydrochloric acid, perhaps thus, — 



2NO + 4HCl + 02 = 2NOCl2 + 2 H,0, 

 then 



Sba -f 3 NOCI2 = 2 SbClg + 3 NO ; 



and afterwards these reactions are repeated indefinitely. But, whether 

 they represent the precise order of the chemical changes or not, 

 there is no question that here, as in the complex reactions of the sul- 

 phuric acid chambers, the nitric acid or its products acts as a carrier, 

 and that the oxygen which combines with the hydrogen of the hydro- 

 chloric acid comes chiefly from the atmosphere. In practice, we 

 usually used, for dissolving 2 grammes of antimony, 30 cubic centime- 

 tres of strong hydrochloric acid and 5 cubic centimetres of the decim 

 nitric acid ; and, although this is only one-fourth of the amount of nitric 

 acid required by the formula generally accepted, it is sufficient to 

 determine a very energetic chemical action, during which a large part 

 of the nitric oxide escapes. The action does not generally come on 

 for some time (fifteen or twenty minutes), although it can be hastened 

 by placing the flask in a warm place. But otherwise we did not heat 

 the acid until almost the whole of the antimony was dissolved. When 

 only a few centigrammes of metal remained undissolved, we connected 

 the flask with a reversed Liebig's condenser and raised the contents to 



