180 Dr. Wilson on the Decomposition of Water by Platinum 



abandoned them as soon as I found I could render Mr. Grove 

 no assistance by means of them. 



It would be difficult to conceive a more rapid and effectual 

 way of raising a body to a white heat than that afforded 

 by the combustion of iron in oxygen. I took for granted 

 also (as it afterwards appeared, too hastily) that the metal could 

 not but be saturated with oxygen and converted into a de- 

 finite oxide, which would be chemically ijidifferent to each of 

 the elements of water, and if it decomposed it at all, would 

 reject both its constituents. The convenient way, moreover, 

 in which the globules of oxide detach themselves and fall 

 into the water, and the rapidity with which the whole process 

 goes on, make it a very easy matter to collect in considerable 

 quantity whatever gases are evolved. A stoppered bottomless 

 jar of the ordinary construction for the iron-wire experiment, 

 and of 291 cubic inches' capacity, was made use of in the fol- 

 lowing trials. Eighteen experiments were made with it, and 

 from 100 to 110 grains of fused globules were obtained from 

 each combustion. A test-tube, with a funnel fixed into it 

 by a perforated cork, and filled with water, was arranged so as 

 to receive the gas. In some experiments it was placed within 

 the oxygen jar, so that the coil of wire when introduced hung 

 close to it, a piece of tin plate being arranged so as to guide 

 the globules within the edge of the inverted funnel. In the 

 greater number of trials however the tube and funnel were 

 placed outside of the vessel containing the oxygen, and an 

 inclined plane of tin plate was so placed as to carry the 

 globules past tlie edge of the jar, and within the mouth of 

 the funnel. No difference of result was observed in experi- 

 ments made in both ways, but the latter arrangement was 

 preferred as more convenient, and as enabling more oxygen 

 to be employed at each trial. 



In all the experiments, permanent gas was evolved when 

 the fused globules fell into the water. This statement is to 

 be considered as applying to each combustion considered as 

 a whole ; for individual globules were frequently observed to 

 give off no gas at all, or to evolve so very little, that it might 

 be air separating from the water, in which it had previously 

 existed in solution. The quantity of gas obtained at each 

 combustion varied greatly. Sometimes as much as a cubic 

 inch was procured, more frequently only half that quantity, 

 and occasionally less. The globules from thick coils of wire 

 gave off a larger volume of gas than those from thin ones. 



Portions of the gas were transferred to a Grove's eudio- 

 meter over water, and exposed to a white-hot platinum wire. 

 They did not kindle or detonate, nor were they sensibly 

 diminished in volume. Other portions were subjected to 



