SCIOPTICON MANUAL. 189 



EXPERIMENTS WITH THE LANTERN MICROSCOPE. By 

 filling a glass trough with diluted sulphuric acid, and 

 dropping into it a few pieces of granulated zinc, the 

 decomposition of water may be shown to an entire au- 

 dience. Aided by a six-cell Smee's, or Grove's, battery, 

 and a small thin tank, the power which palladium pos- 

 sesses of absorbing nine hundred times its volume of 

 hydrogen may also be shown; the snake-like contortions 

 of the strip of metal, and the bubbles of gas escaping 

 on the reversing of the current, proving very interesting. 



The crystallization of salts may also be shown by 

 placing a drop of a strong solution of Epsom salts, or 

 sulphate of copper (blue vitriol), on a piece of glass of 

 suitable size. 



Another effective result is obtained by placing in the 

 glass tank a small horse-shoe magnet, and dropping 

 around it some iron filings, which will bo found to ar- 

 range themselves, or rather be attracted by the magnet, 

 in a most extraordinary manner. 



Exhibitions of microscopic objects by the aid of the 

 magic lantern in the drawing-room sometimes fail to 

 give that complete satisfaction which is desirable, owing 

 to- attempts being made to show them on too large a 

 scale in proportion to the light employed. We have 

 given very satisfactory exhibitions on a sheet of Im- 

 perial (22x30) white card-board, fastened by drawing- 

 pins to a board, and fixed against some books or on a 

 chair. In this way the proboscis of a blow-fly may be 

 enlarged to two feet in length, and this is found to be 

 quite large enough for most private assemblies. 



It is desirable to have two or three sets of lenses, of 

 different powers, with the microscope, which are varied 

 to suit the object to be exhibited ; and it is important 

 to observe that when minute objects are being exhibited, 



