1012 Transactions of the American Institute. 



Dr. Vanderweyde. — The property which confers its great value 

 upon gunpowder is that it cannot be exph)ded by ordinary concussion, 

 and it is even difficult to ignite it with a flame. There is a common 

 lecture-room experiment which I have often performed and it is this : 

 I have taken a basin of alcohol and set it on fire, and then taken a 

 handful of iron filings mixed with gunpoAvder and shaken them into 

 the flame. The filings will burn and the gunpowder will not. Iron 

 is actually more combustible than gunpowder. 



Mr. "John Phin. — I have tried the experiment described. by Dr. 

 Variderweyde, and ' it succeeds perfectly. There is another experi- 

 ment which illustrates the same thing. I have strewed, a train of 

 gunpowder on a board for a length of two or three feet and tlien 

 crossed it at right a,ngles with a 'train of fulminating mercury. On 

 fii4T>g the train of powder at on€ end it burns slowly up to the 

 fulminate, which explodes and blows the powder all about. In 

 generjil the powder ' is extinguished at the crossing of the train of 

 fulminate, and the part of the train of powder whidi lies beyond this 

 point does not burn. 



Zoological Discoyeeies in MadagasciVr. 

 Recent explorations of M. Grandidier prove that, at the time the 

 island was inhabited by the gigantic dodo or epiornis, it also pos- 

 sessed-certain huge pachydermata, strongly resembling one of the 

 most remaVkable African species, viz. : A kind of hippopotamus. 

 The remains of about fifty hippopotami, mingled with those of the 

 dodo, were found in a marshy district on the west coast of Mada- 

 gascar. 



Basement Flooes. 



Professor Rolliston, of Oxford, in a communication to the London 

 Lancet, calls attention to certain important points which the study 

 of recent sanitary literature and of mechanical house building has 

 impressed upon his attention. The most important is that relating 

 to floors and foundations. It seems to be clearly made out that the 

 interposition of a layer df impervious substance, of whatever kind, 

 so, that it be impervious, between the level of the ground water in 

 the soil, and the floor of the house built upon it, confers upon such a 

 house an immunity m cholera epidemics. Facts in support of the 

 truth of this statement are contained in a recent paper published by 

 Professor Pfeiffer; and Dr. Kolleston is of opinion that the indi- 



