486 



and let the zinc be melted in a crucible or iron ladle. 

 Pour the heated quicksilver into a wooden box, and im- 

 mediately after pour the melted zinc in it. Then shut 

 up the box and shake it for about half a minute. After 

 this you must wait until the amalgam is quite cool, or 

 nearly so, and then you may mix some grease with it 

 by trituration. If the melted zinc be poured into the 

 quicksilver when cold, a very small portion of the for- 

 mer will be amalgamed, the rest remaining in lumps of 

 different sizes.' 



The following drawing and description of a simple 

 Electrical Machine and conductor, is from Cavallo. 



The figure represents an 

 electrical machine of the 

 simplest sort. G E F, is a 

 strong board, which sup- 

 ports all the parts of this 

 machine, and which may be 

 fastened to a strong table by 

 means of one or more iron 

 or brass clamps, as at Q. 

 The glass cylinder A B, 

 quite clean and dry in its 

 inside, is about ten inches 

 in diameter, and is furnish- 

 ed with two caps either of wood or brass, into which its 

 two short necks are firmly cemented.* Each of these 

 caps has a pin, or projection, or pivot, which turns in a 

 hole through the wooden pieces A and B, which are ce- 

 mented on the top of glass pillars, (or pillars of baked 

 wood,) B E and A G, which are firmly fixed to the bot- 

 tom board G E F. One of the above mentioned pro- 

 jections passes quite through the wooden piece, as at A, 

 and has a square termination, to which the winch A D 

 is applied and secured on by means of a screw-nut. 

 Then by applying the hand at D, the operator may turn 

 the cylinder, &c. Sometimes the part A C, of the 



* The best cement for this purpose is made by melting and incor- 

 porating; together five parts of resin, four of beeswax and two parts 

 of powdered red ochre. 



