A new Fulminating Silver. 269 
which tended to prove that they are different compounds. ‘Thus, | found that the 
new compound, exploded when heated from about 350° to 370° of Faht.; whilst 
Howard’s compound required an increase of 100° or from about 450° to 470° Faht. 
to explode it. Howard’s compound readily dissolves in boiling water, as M. Liebig 
observed, but the white silky crystals are rapidly deposited as the solution cools, and 
very little remains in solution at the temperature of the air, The new compound 
is nearly insoluble in boiling water; I could not dissolve half agrain of it in several 
ounces of water, kept boiling for some time in a platina crucible. Even the small 
portion that dissolves is found to have acquired new properties, for on being collected 
and dried, it will not explode in chlorine, and is probably by a loss of acid, converted 
into Howard’s compound. 
Howard’s compound, however carefully prepared and dried ; whether in crystals, 
or an impalpable powder, does not spontaneously explode in chlorine gas, or in mix- 
tures of this gas with other gases. | Whereas, the new compound, whether dried at 
60° or at 212° and even before it becomes pulverulent from loss of moisture, readily 
explodes under such circumstances. 
According to my experiments, Howard’s compound contains one proportion of 
fulminic acid, and one proportion of oxide of silver; and it has been called fulminate 
of silver: as the new compound appears to contain two proportions of the acid, and 
one of the oxide, it is properly a bi-fulminate of silver. 
5. Experiments on the application of the new Fulminating Silver, as a test for 
Chlorine, §c. 
The chlorine gas employed in the following experiments, was generally made in the 
usual way, by adding diluted sulphuric acid to a mixture of common salt, and black 
oxide of manganese. Occasionally, it was procured from muriatic acid and the same 
oxide. Sometimes the gas was received over water, at other times it was collected in dry 
bottles furnished with ground stoppers. ‘The new fulminating silver, or test, as I shall 
now, for convenience, call it, was made by decomposing fulminating zinc by nitrate of 
silver, as has been stated. It was sometimes dried on a sand bath at a temperature not 
exceeding 212° Faht., and sometimes in the open air. It was always, however, suffi- 
ciently dry to be pulverulent. It was commonly used in very minute quantities ; a simple 
grain serving, on an average, for upwards of fifty,and occasionally for about one hun- 
dred separate experiments. It indicated the presence of chlorine, by instantly ex- 
ploding when brought in contact with this gas, and also with other gaseous mixtures 
in general, which contained chlorine. 
1. The test readily and repeatedly exploded when put into bottles of very impure 
chlorine gas, made a long time and haying no vestige of colour; and also into bottles 
