POPULAR SCIENCE REVIEW. 
the alloy a still lower melting-point than above ascribed to it, as I see that 
the experiments made by Lipowitz with my fusible metal indicate for it a 
much greater fusibility than my measurements.” 
The improved processes for the manufacture and metallurgy of platinum, 
by M. St. Claire Deville, are now generally known to the scientific 
public. The process is based upon the employment of a gigantic 
oxy-hydrogen blowpipe playing upon the metal in a nearly closed 
chamber cut out of lime, and was almost immediately upon its intro- 
duction adopted by the firm of Johnson, Matthey, & Co., the well-known 
precious metal refiners, who have since used it largely in the manufacture 
of platinum. They have recently availed themselves of the presence in 
England of M. Deville and other eminent scientific men to invite a party 
of English and Continental savans to witness one of the grandest metal- 
lurgical feats ever accomplished, — the melting and casting of a mass of 
pure platinum weighing upwards of 2 cwt. This mighty ingot of precious 
metal, by far the largest mass ever before obtained in a single lump, and 
worth £3,840, has recently been deposited in the International Exhi- 
bition. The mould into which it was run was roughly built up of 
refractory limestone ; and the extreme fluidity of the liquid metal is 
well illustrated by the irregularities in the sides of the ingot, it having 
entered the minutest crevices between the lumps of stone as if it had been 
so much water. The sharpness of the impression, and the minute details 
which the melted metal has retained on solidifying, show that platinum, 
when once obtained in a fluid state, is as eminently adapted for fine castings 
as any of the commoner metals. We regret to add, that the vapour of 
osmic acid was given off so abundantly in this operation as to seriously 
affeejj M. St. Claire Deville, who superintended the fusion. He was 
obliged to return to'Paris, where he for some days suffered severely. 
HE duties of the jury in Class 14, Photograph}’, in the International 
Exhibition, are likely to be very onerous, on account of the large 
assortment of excellent photographs and apparatus displayed, not only in the 
British Department, but throughout all, or a large majority, of the foreign 
and colonial courts. The art of photography constitutes one of the chief 
efforts of science which has advanced with giant strides since the period 
of the Exhibition of 1851. With the introduction of the collodion process, 
which dates from the latter part of that year, and was actually employed 
by its inventor, Mr. Archer, within the building in Hyde Park, so much 
has been already accomplished that the World’s Mart teems with innu- 
merable exampdes of its successful application. The records of astrono- 
mical and meteorological phenomena, the adaptation to portraiture and to 
the illustration of foreign races, their manners and customs, remarkable 
landscape scenery, and the characteristics of distant regions, — on every side 
the visitor to the International Exhibition is reminded of the vast impor- 
tance of photography, and of the attention it must have received during 
the intervening ten years. We are enabled to admire the results of our 
continental rivals, and to compare the life-size portraits of Mr. Mayall and 
other British exhibitors with those taken by M. Hansen, of Copenhagen. 
PHOTOGRAPHY. 
