On Mounting Objects in Phosphorus. By J. W. Stephenson. 165 



2. The phosphorus must be introduced with the least possible 

 exposure to the air, as phosphoric acid is otherwise very readily 

 formed, and this ruins the preparation. 



3. The solution of phosphorus must be perfectly clear and 

 bright. 



Of not much less importance is the necessity of having a vessel 

 of water at hand, in order that the bibulous paper which has been 

 used in the process, may be instantly submerged so as to prevent 

 the danger of spontaneous combustion, and also to avoid the 

 inhalation of fumes from the phosphorus which are prejudicial to 

 health. 



In the preparation of the solution a 2-drachm bottle without 

 any contraction for the neck is employed. A filter of bibulous 

 paper is formed, accurately to fit the bottle by folding the paper 

 down and around a small ruler or other cylinder of wood, of such a 

 size, that with the paper around it, it may fit tightly into the bottle, 

 to the bottom of which it is forced, and the wood withdrawn. The 

 filter is now moistened with a few drops of bisulphide of carbon, all 

 excess beyond that which is necessary for this purpose being 

 dashed out, and a piece of stick phosphorus, as pure as possible, 

 and say ^ or f of an inch in length, dropped into the filter, and the 

 bottle corked ; the vapour from the bisulphide instantly acts upon 

 the phosphorus, and in about half an hour or less it will be 

 entirely dissolved, but still remaining in the filter. By taking a firm 

 hold of the edge of the filter with a pair of forceps, and very 

 slowly drawing it upwards, a partial vacuum is formed beneath the 

 filter, and the pressure of the atmosphere on the surface of the 

 solution forces the phosphorus through the paper, and the brilliant 

 highly refracting fluid is seen at the bottom of the bottle. The 

 filter now withdrawn must be instantly plunged in water for reasons 

 already given. 



The phosphorus being thus prepared, the mode of mounting 

 is as follows. We will suppose the object to be diatoms, and of 

 course adhering to the cover. 



In the first place a ring, somewhat smaller than the thin glass 

 cover, is formed on the slide in the usual way, using for the 

 purpose a solution made of glue, mixed with a small quantity of 

 honey, which preparation when cold should form a somewhat stiflf 



The thin cover is now placed on the glass slip, but being raised 

 on one side by a piece of bristle or fine wire, it is only the opposite 

 ■ side which touches the glutinous ring, to which it adheres. The 

 reason for tilting the cover will be seen hereafter. 



The next step is the real mounting, which is efiected by means 

 of a pipette ; this is made of glass tubing (say ^ of an inch in 

 external diameter), drawn out to a fine point at one end, the other 



