Intelligence and Miscellaneous Articles. 527 



and the liquid. The volume of the gas disengaged by zinc under- 

 goes no change in the course of several daj^s ; the volume of the gas 

 produced by the pile diminishes rapidly. The following are the 

 numbers furnished by the experiment : — 



4h 20" 4'' 25"" 4'' 40" S*- 5" S^ 55'" 12'' 



84 80 77 70 66 50 



The action was afterwards prolonged indefinitely, but the remainder 

 of the gas was no longer absorbable ; the gas is consequently com- 

 posed of an absorbable portion, and of a portion which behaves like 

 ordinary hydrogen. The absorbable portion sometimes amounted to 

 three-fourths of the total volume, but most frequently it was less 

 than half; occasionally no absorption took place. 



To ascertain the relation existing between the formation of this 

 absorbable gas and the current, I measured the intensity (of the 

 latter) with a tangent compass, and reduced the results to the 

 unities of time and intensity. I ascertained that the volume of hy- 

 drogen may attain a maximum or remain at a lower value ; in the 

 former case it was not absorbable, in the latter, absoi-ption took 

 place. We may say, therefore, that in order to disengage a volume 

 of absorbable gas, we must employ more electricity than in the pro- 

 duction of a similar volume of ordinary gas. 



These facts may be interpreted in two ways ; we may suppose 

 that the hydrogen disengaged by the pile is produced in a peculiar 

 molecular condition whilst taking the gaseous form under the influ- 

 ence of the electric current, nearly as in the case of the oxygen 

 which is electrified and modified at the positive pole. This con- 

 clusion is the only possible one if the gases disengaged be chemi- 

 cally pure. 



But if, contrary to the generally received opinion, the gas collected 

 at the negative pole be a mixture of the two constituent elements 

 of water, we should have in contact two bodies which may combine 

 under the influence of the platinum wire to reconstitute water. 



Further experiments must decide the question, but whatever solu- 

 tion may be arrived at, the fact is important, as from it we shall 

 derive the knowledge either of a new state of hydrogen, or of a mode 

 of decomposition of water by the pile, in which both gases are dis- 

 engaged at the same time. — Comptes Rendus, March 6, 1854, p. 443. 



Hansen's electro-magnetic engraving machine. 

 This machine is somewhat on the principle of the well-known 

 planing machine. The drawing to be copied and the plate to be 

 engraved are jjlaced side by side, on the moveable table or lid of the 

 machine; a pointer or feeler is so connected, by means of a hori- 

 zontal bar, with a graver, that when the bar is moved, the drawing 

 to be copied passes under the feeler, and the plate to be engraved 

 passes in a corresponding manner under the graver. It is obvious 

 that in this condition of things, a continuous line would be cut on 

 the plate, and, a lateral motion being given to the bed, a series of 



