106 
CAPTAIN NOBLE AND ME. E. A. ABEL ON EIEED G-UNPOWDEE. 
The coil of wire was not to be found, but portions of it were observed welded to the 
sides of the cylinder. 
Now we know that platinum is readily volatilized when exposed to the hydrogen- 
blowpipe at a temperature of about 3200° C., and therefore, if the temperature of 
explosion had approached this point, we should have expected the very fine wire to be 
volatilized; remembering the low specific heat of platinum, we should furthermore have 
been warranted in expecting more decided signs of fusion in the sheet metal. 
Again, in experiments 84, 85, and 68, pieces of platinum wire -03 inch (0‘75 millim.) 
in diameter and 4 inches (100 millims.) long were placed in the cylinder with consider- 
able charges of It. L. G. and F. G. In none of these experiments did the platinum 
melt, although, as in the case of the sheet platinum, there were signs of fusion on the 
surfaces of the wires. In experiment 79, however, in which platinum wire was placed 
with a corresponding charge of the Spanish powder, the wire was fused, with the exception 
of a small portion. With this powder, indeed, which is of a very different composition 
from the English powders and decidedly more rapidly explosive in its nature, it is quite 
possible that a somewhat higher heat may have been attained. But, as in one case the 
platinum wire was nearly fused, and in others it only showed signs of fusion, the con- 
clusion we draw from the whole of these experiments on the fusion of the platinum is 
that the temperature of explosion is higher than the melting-point of that metal, but 
not greatly so. Now, according to Deville, the melting-point of platinum is nearly 
2000° C. ; and hence we have a strong corroboration of the approximate accuracy of 
the theoretical temperature of explosion at which we have arrived, viz. 2231° C. 
P. MEAN SPECIFIC HEAT OF LIQUID PEODUCTS. 
We have already given the specific heat of the liquid products when in the solid form. 
If we assume the temperature above specified to be correct, a mean specific heat of the 
liquid product of ’4090, or a total mean specific heat of the entire products of - 3094, 
would result, being an increment of about 67 per cent. ; and this, judging from the 
analogy of the case we have cited, does not appear an improbable conclusion. 
Q. PEOBABLE EXPANSION OF NON-GASEOUS PEODUCTS BETWEEN ZEEO AND 
TEMPEEATUEE OF EXPLOSION. 
So far as we are aware there were, prior to our experiments, no data existing as to 
the behaviour of the non-gaseous products of combustion at the high temperature 
involved, except perhaps the experiment made by Bunsen and Schischkoff, who exposed 
on platinum foil the solid residue in an oxyhydrogen jet, and concluded, from there 
being no ebullition, that at the temperature of 3300° C. the tension of the resulting 
vapour did not reach one atmosphere. Taking the circumstances into account, we may 
indeed doubt if the residue itself actually reached the temperature we have uamed ; 
but the experiment would at all events prove that, at the temperature which we find to 
be that developed by explosion, the solid or liquid products are not in the state of 
vapour, or at least that the small portion volatilized had but an insignificant tension. 
