292 Notes on Chemistry, &fc. 



Art. XVI. — Notes on Chemistry, &fc.; by J. W. B^ailey, A.cting 

 Prof. Cheni. &:c. U. S. Mil. Acad. West Point. 



1. Substitute for Frogs in Galvanic Experiments. — Persons who 

 may have occasion to repeat Galvani's experiment on the legs of 

 frogs, will doubtless be pleased to hear of some substitute, which 

 will enable them to dispense with the disgusting operations of clean- 

 ing, skinning, &;c. which are necessary before the legs of a frog can 

 be used. I find that a leg of the common grasshopper may be made 

 to exhibit the muscular contractions ; and as it appears to be easily 

 affected by electricity, can frequently be obtained when frogs can- 

 not, can be prepared at a minute's notice, and retains its irritability 

 for five or ten minutes, it forms an excellent substitute. 



The method of preparation consists merely in removing, with a 

 sharp penknife, from each side of the thick part of one of the leap- 

 ing legs, a portion of the skin, so as to expose the flesh ; then by 

 laying the under side of the leg upon a small piece of moistened 

 zinc, and bringing a piece of copper in contact with the flesh ex- 

 posed on the upper side, no motions will be observed until the cop- 

 per also touches the zinc, when quick movements or jerks of the 

 lower part of the leg will be seen, each time that contact is made. 

 In Fig. 1 , Z is the zinc, C the copper. A, B the part of the leg 

 which will be observed to move. 



2. Washing Bottles. — The admirable contrivances of Berzelius 

 and Gay-Lussac, by means of which a substance to be washed upon 

 a filter, may be supplied with water as fast as it is required, are not, 

 I believe, so well known in this country, as their merits entitle them 

 to be. 1 have used them with so much satisfaction, that I am in- 

 duced to send the accompanying drawings and description ; believ- 

 ing that they will be useful to some persons, who may be engaged 

 in analysis or pharmaceutical preparations, and to whom they may 

 be unknown. 



Berzelius remarks, (Traite, Tome VIII, p. 270,) "Few modern 

 instruments are so valuable to the practical chemist, as these simple 

 washing bottles, since by means of them, the washing may be con- 

 tinued during all the time the operator may be obliged to be absent, 

 and during his presence it requires no particular attention," except 

 to see that channels do not form, which may lead the water off too 

 rapidly. 



