APPENDIX. 
An account of a large Electro-Magnet,* made for the Laboratory of 
Yale College ; by Josepu Henry and Dr. Ten Eyck. 
(Extract of a letter to Prof. Silliman, accompanying the Magnet.) 
E magnet is constructed on precisely the same principles as 
that described in the last number of the Journal. It weighs 594 Ibs. 
avoirdupois, (exclusive of the copper wire which surrounds it,) and 
ip se 
* This magnet is now arranged in its frame, in the laboratory of Yale Col- 
- Being myself out of town when the instrument arrived, the necessary ex- 
periments and fixtures were satisfactorily made by Mr. C. U. Shepard, (Chem. 
Assis.) and Dr. Titus W. Powers, of Albany, who was so obliging as to bring the mag- 
Th t es ag. { hh + 2 + ~ me So was 
substantiated the statements of Prof. Henry.{t He has the honor of having 
der his direction, The length of the wires being agreed upon, the winding was 
done by Dr. Ten Eyck, and the experiments were mutually performed.—Ed. 
It may be worth while to state a single experiment, which I made with a view 
to learn the chemical effects of this instrument. As its magnetic flow was so pow- 
erful, Thad strong hopes of being able to accomplish the decomposition of water by 
ts means, My experiment, however, which was made as follows, proved unsuc- 
cessful. The battery being immersed, to the extremities of the magnet were applied 
wa tron polished plates of iron, terminating in flattened wires, which were — 
j | ae Cal a = ¢ 1 . rs Jéth ey ae to! 
y apparatus for decomposing 5 g 
tened by the use of cups of mercury: not the slightest decomposition was, however, 
observable, Aware, that had any chemical effect been produced, this arrangement 
could have decided nothing, (except perhaps from the degree of energy in the de- 
oS pevmags as respects the point whether simple magnetism is adequate to decom- 
had the decomposition ensued, pure magnetism might have been considered as the 
decomposing agent. But as my preliminary experiment was unsuccessful, [ pro- 
feeded no farther; [ hope, however, to resume the research hereafter, under more 
favorable circumstances. C. U. Sreparp. 
Von. AX—No: 1. 26 
