210 Dr. John Davy on the 



a mortar, were put under an inverted glass in which were con- 

 fined a honey bee and two small insects of the knat kind. In 

 about five minutes they had all been rendered motionless ; one of 

 the small flies did not revive ; the other and the bee recovered in 

 a kw hours, symptoms of revival appearing even before they 

 were taken from beneath the glass into the open air. Probably 

 had the experiment been made at another season, in summer or 

 autumn, the effect would have been different ; be this as it may, 

 the result was not of a kind to induce me to make at the time any 

 further trials of the leaves, especially after instituting some with 

 the hydrocyanic acid, the fatal agency of which exceeded my 

 expectations. 



With a view to answer your inquiries respecting this acid, I 

 paid attention to quantities. Two glass tubes, each closed at one 

 end, a small and a larger one, were selected for the experiments ; 

 the larger of three cubic inches and a half capacity, and seven- 

 tenths of an inch wide, the smaller only one-tenth of an inch in 

 width, and little more than an inch long. The small tube, charged 

 with three-tenths of a grain of prussic acid, was introduced into 

 the larger, in which had just before been placed three flies. 



The tube was finally closed with a cork. In less than two 

 minutes one of the smaller flies, and also the larger, dropt down, 

 and, after a few convulsive movements, became motionless, as did 

 the other in about half a minute more (it was further removed 

 from the acid), but without convulsive action. Taken out in less 

 than half a minute, and exposed to the air of the room at 55° 

 Fahrenheit, they did not revive. The small tube, immediately 

 weighed, had not sustained any appreciable loss. 



Repeated the experiment, using the same portion of acid on 

 another fly (a Heteromyza). It became motionless in as short a 

 time, but it revived when exposed to the open air. Placed again 

 in confinement, with only *04 grains of prussic acid in the small 

 tube, in five minutes it became motionless. Immediately taken 

 out, it was found revived after an hour, and so active that it 

 escaped by taking flight. 



Placed a honey bee just caught in the garden at noon, under a 

 wine glass inverted, of about four cubic inches capacity, with the 

 small tube charged with *16 grains of prussic acid. In about 

 two minutes the bee fell down and was convulsed in its legs and 

 abdomen ; all motion ceased in about eight minutes. Taken out 

 immediately, symptoms of revival appeared in about three hours ; 

 soon after it was standing on its legs, but not active : the fol- 

 lowing morning it was found dead. 



