290 Dr. Harems Description of Voltaic Series, fyc. 



end of each of the lead rods is soldered to a piece of sheet copper. 

 The pieces of copper, thus soldered to the lead rods, are then to be 

 placed under the pivots, which are of course to be connected with 

 the termination of the series. The last mentioned connexion is 

 conveniently made by means of straps of copper, severally soldered 

 to the pivots and the poles of the series, and screwed together by a 

 hand-vice. Each pair consists of a copper and a zinc plate, united 

 by solder at the upper edge, where the copper is made to embrace 

 the edge of the zinc. The three remaining edges are made to enter 

 grooves in the wood, being secured therein by cement. For each 

 inch in the length of the trough there are three pairs. In the series 

 represented by fig. 1, there are one hundred pairs of fourteen inches 

 by eight ; in that represented by fig. 2, there are seven hundred 

 pairs of seven inches by three. The latter will deflagrate wires too 

 large to be ignited by the other, but is less powerful in producing a 

 jet of flame between the charcoal points, or in giving a shock. 



Fig. 2, on the opposite page, represents a series which comprises 

 two Cruickshank deflagrators, so constructed as to co-operate in one 

 circuit by an adequate communication between their poles, and be- 

 ing so associated with a lever, as to be made, by means of it, to re- 

 volve simultaneously. They may be made to act either collaterally, 

 as a series of 350 pairs, or consecutively, as 700. As the plates are 

 seven inches by three, when used collaterally, they are equivalent to 

 350 plates of seven inches by six. 



Combustion of Phosphorus in nitrous oxide gas.* 



There is a striking backwardness in the oxides of nitrogen to part 

 with their oxygen to phosphorus, until it be intensely ignited, either 

 by an incandescent iron, or by the access of uncombined oxygen. 



This characteristic in the case of nitrous oxide, may be illustrated 

 by means of an apparatus like that employed for the combustion of 

 phosphorus in oxygen with a tall cylindrical receiver, and a tube de- 

 scending through the neck, and along the axis of the receiver, termi- 

 nating in a capillary orifice over the cup for holding the phosphorus. 

 The upper end of the tube, outside the receiver, is furnished with a 

 cock, to which a gum-elastic bag inflated with oxygen is attached. 



Under these circumstances, the receiver having been exhausted, 

 and filled with nitrous oxide ; phosphorus, previously placed within 

 the cup, may be melted without taking fire. But as soon as the cock 



* An apparatus employed by Dr. Hare for exhibiting the same peculiarity in 

 the case of nitric oxide has already been published in this Journal. 



