294 Chemical Preparations. 



ploding heat as may be. Having dried it, burn a few grains upon 

 paper, when the explosion will be found equal to that of detonating 

 silver. The paper will be shivered to pieces, and the coal of fire 

 annihilated, if the powder be well dried. 



I think the powder burns with most violence taken after the alkali 

 has acted on the fulminating mercury two days, but a great change 

 is effected upon the composition in a littfe time. Examine the con- 

 tents of the glass on the fourth day, and the fulminating mercury 

 will be found subsiding ; the peculiar action, by which its stiffness 

 was created and kept up, having gone by, and the detonating quali- 

 ties of the powder being lost. If the composition be now pressed and 

 dried, it will explode very mildly, and without flame, or at least with- 

 out appearance of flame in a light room. 



I poured a saturated solution of caustic potash into one ounce of dry 

 fulminating mercury, and the next day I pressed it as dry as I con- 

 veniently could, and laid it aside for half an hour, when it exploded 

 spontaneously. I observed when I took it out of the press that it 

 had become hot, but thought no more of it until it exploded. 



Into a ladle of boiling solution of caustic potash I stirred a quanti- 

 ty of fulminating mercury, and then poured the mixture upon a filter : 

 on cautiously pressing the filter, the composition took fire whilst it 

 was yet as thin as paste. 



I think the powder cannot be dried so as to preserve its detona- 

 ting qualities. The potash, though retarded in its operation, never- 

 theless continues it, and in a few days fulminate of potash is genera- 

 ted. I prepared a quantity of these crystals to send you, but they have 

 deliquesced, and I have not inclosed them. These are not " true 

 fulminates,''^ having no fulminating disposition ; and the term can be 

 true only as applied to the triple compound, whilst a peculiar action 

 is going on between the fulminite of mercury and the potash, so far 

 as caustic potash is concerned. Lime water, carbonate of potash, 

 carbonate of soda, and ammonia, all blacken fulminating mercury, 

 and generally improve the explosive qualities in the first instance, but 

 injure or ruin the preparation soon after. Solution of chloride of lime 

 has no action upon fulminating mercury ; iodine gives the mass a Ver- 

 million color, and spoils its fulminating qualities. 



The exploding point of fulminating mercury and caustic alkali is 

 varied by the concentration of the caustic potash. If the potash be 

 diluted to various degrees of strength, there will be corresponding 

 points of temperature at which the product will be ignited. There 

 will likewise be corresponding powers oi detonation: 



