EFFECTS OF HEAT ON FLUIDS. 425 



colour, and had a few black specks floating in it, which I judged 

 to be minute portions of the same crust which had formed on 

 the platinum wire, and which had become detached. 



The experiment was repeated with chloride of iodine, and 

 with the same result, except that the quantity of oxygen was 

 greater ; I collected as much as half a cubic inch in some 

 experiments, from an equal quantity of chloride of iodine ; the 

 platinum wire, however, was more quickly acted on than with 

 the bromine, and also to some extent the glass of the tube 

 around it. 



Melted phosphorus was exposed to the heat of the voltaic 

 disruptive discharge by taking this between platinum points 

 in a tube of phosphorus, similarly to an experiment of 

 Davy's, but with better means of experimenting; a consi- 

 derable quantity of phosphuretted hydrogen was given off, 

 amounting in several experiments to more than a cubic inch. 



A similar experiment was made with melted sulphur and 

 sulphuretted hydrogen given off, but not in such quantities as 

 the phosphuretted hydrogen. I tried in vain to carry on these 

 experiments beyond a certain point ; the substance became 

 pasty, mixed with platinum from the arc, and from the diffi- 

 culty of working with the same freedom as when they were 

 fresh, the glass tubes were always broken after a certain time. 

 Had I time for working on the subject now, I should use the 

 discharge from the Ruhmkorff coil, [which had not been in- 

 vented at the period of these experiments. At a subsequent 

 period, when this discharge was taken in the vacuous receiver 

 of an air-pump from a metallic point to a metallic capsule 

 containing phosphorus, a considerable yellow deposit lined 

 the receiver, which, on testing, turned out to be allotropic 

 phosphorus. No gas is, however, given off. I had an air- 

 pump (described 'Phil. Trans.' 1852, p. 101) which enabled 

 me to detect very small quantities of gas, but I could get 

 none. It was in making these experiments that I first de- 

 tected the striae in the electric discharge, which have since 

 become a subject of such interesting observations, which are 

 seen, perhaps, more beautifully in this phosphorus vapour 

 than in any other medium, and which cease, or become very 

 feeble, where the allotropic phosphorus is not produced. 



