9i Mr, DeHchai'*s Explanation of [Feb. 



4. Superoxymuriate of potassa 4*5 



Flowers of sulphur 1*5 



Charcoal powder . . . . , 1*5 



Nitre 2-5 



This andNos. 5 and 8 are the third best. 



5. Superoxymuriate of potassa 4*0 



Flowers of sulphur 1-0 



Charcoal powder 1*0 



6. Superoxymuriate of potassa 1*0 



Sulphuret of antimony 1*0 



This and No. 7 are fifth best, but they leave a hard cake of 

 crocus of antimony, which adheres very strongly to the appa- 

 ratus. 



7. Superoxymuriate of potassa 1*0 



Sulphuret of antimony I'O 



The proportions of this powder were taken by volume. 



8. Superoxymuriate of potassa 2*0 



Dried charcoal powder 1*0 



9. Superoxymuriate of potassa 1*0 



Dried charcoal powder 1*0 



10. Superoxymuriate 'of potassa 3*0 



Dried gunpowder 2*0 



This is the best. 



11. Superoxymuriate of potassa 1*0 



Gunpowder, in fine powder 1*0 



This is the second best. 



After numerous trials with these, their comparative regularity 

 in producing the desired effect was calculated to be as nearly as 

 -possible, as has been noted in the above Hst. But I found that 

 even No. 10 was not so uniform as was necessary for Col. Yule's 

 object. I had now, however, almost doubted of success, when 

 it occurred to me to try the composition, which has since been 

 found to succeed for more than 100 successive times, without 

 leaving any, residuum to stop the firing. Of the composition of 

 this powder, and some cautions necessary to be attended to in 

 its prepamtion, an account will be given in a future paper. 



It was with this powder that I performed the experiments, 

 which presented those striking results of which I have now to 

 give a brief account. 



I was led to these with the hope of elucidating still further 

 than I had previously done a particular view of caloric, of which 

 I have, for six years past, given an account in my chemical 

 classes. I availed myself of the use of Col. Yule's apparatus to 

 commence the investigation, and I am still occupied with it. At 



