OHAPTEE III. 
CERTAIN PYRO-ELECTRIC QUALITIES OF THE ALLOYS OF 
PLATINUM. 
EXPLANATION. 
The immediate object of the investigations given in this chapter 
is to determine the approximate effect produced on the galvanic and 
the thermo-electric properties and on the density of platinum by alloy- 
ing this metal with small amounts of some other metal. Not being 
sufficiently versed in the chemistry of the platinum group myself, and 
not wishing to burden my associates with the tedious task of rigorous 
chemical purification, I contented myself with a practical survey of the 
electrics of the platinum metals; nor was there enough time at my dis- 
posal to justify the attempt of an exhaustive examination. 
The plan which under these circumstances suggested itself to me was 
to have a homogeneous ingot of platinum drawn down to a single length 
of tolerably thin wire, and then to compare the electrics of consecutive 
parts of this wire in their original and alloyed state with each other. 
A coil of wire consisting of a single length about 131 meters and weigh- 
ing nearly 420 grains was drawn down for me by the Malvern platinum 
works. The wire itself, weighing about 3.2 grains per meter, was 
nearly 0.043 cm in diameter. I was the more easily able to acquiesce in 
this simple method of obtaining a platinum body for the alloys since, 
in earlier experiments of our own, samples of platinum and platinum 
alloys obtained in Paris could be fused over without producing any 
serious variation of constants, and since I inferred from the researches 
of Deville and Troost that the intense heating of platinum on a lime 
hearth before the oxyhydrogen blow-pipe, was itself a sufficient method 
of purification so far as the elimination of volatile and oxydizable con- 
stituents is concerned. Moreover, it has been stated in Chapter I that 
the general plan of work was to be such that special stress might be 
put on the effect of vanishing quantities of an alloying metal added to 
platinum. Hence I looked principally to obtaining a metallic body for 
the alloys showing fixed properties before and after melting. 
In the course of the investigation, however, it became painfully ob- 
vious that the labor of making the alloys, the fusions, rolling and wire 
drawing, the experimental evaluation and the computation of the con- 
stants had been very much underrated. I found, in other words, after 
about oue half of my investigation had been completed, that the amount 
of work expended could have been justified only ii the work had been 
m (780) 
