854 TnANSACTioxs of tjb^e American Institute. 



of the most explosive substances we have. It is made by combining 

 chlorine and ammonia, and drying the precipitate. 



A desultory discussion on various explosive materials closed the 

 debate, whereupon the association adjourned for one week. 



November 5th, 1868. 



Professor S. D. Tillman in the Chair ; Mr. C. E. Emery, Secretory. 

 The chairman opened the proceedings by reading the following 

 notes on science and art : 



Dynajmite, 



The London Mechanic^'' Magazine lately gave an account of 

 experiments with dynamite, which is simply a mixture of nitro-gly- 

 cerine with a finely powdered silicious mineral, showing that it may 

 be handled with impunity, and even exposed to fire without danger ; 

 but hearing that the engineers of the Hoosic tunnel did not regard 

 dynamite as any more safe than plain nitro-glycerine, we declined 

 to give further publicity to that account. A late number of the 

 same journal says : " The recent exi^losion at Pemberton seems to 

 show that dynamite is not so safe an explosive as has been supposed." 



Singular Effects of Lightning. 



Gen. Morin reports to the French Academy that in the depart- 

 ment of Toune, the lightning set a hamlet on fire. Several cottages 

 were burned ; in the drawers of one of them were some gold coins 

 and twenty-five franc silver pieces. The electric force converted the 

 silver in four singularly shaped ingots, but left the gold coin almost 

 unchanged. The gold pieces adhered to each other, and were cov- 

 ered with a slight incrustation, but the eftigies on each were still 

 visible. 



New Method of Bleaching. 

 Wild's magneto-electric machine is now being used in a sugar 

 refinery in England for the purpose of bleaching sugar, doubtless to 

 ozonize the air which is used as the bleaching agent. Xo report has 

 yet been made as to the feasibility of the process. 



The Prismatic Colors. 

 A correspondent of The London Builder says the usual method of 

 observing prismatic colors is by looking at any object through a 



