24 
Proceedings of the Royal Society 
form when cooling is extended over a long time, probably because 
working under some to us at present unknown law, it is easier for 
it to crystallise in that form than in the octahedral or cubical one. 
This might indeed form a subject for a very interesting research, 
“ Whether any preference is shown by a body crystallising in two 
forms, to crystallise in one of the forms rather than in that of the 
other, and under what conditions it takes place to most advantage V’ 
From what has been said there can now be but little doubt as to 
whether these crystals are diamonds or not — that in point of fact 
they certainly are — and the questions now naturally arise as to 
whether they can be made of sufficient size t6 be of any practical use 
or value 1 if so, at what cost ? and finally, whether they can be 
produced on a large scale without colour and with the lustre of the 
natural gem, so as to be available for ornamental purposes ? 
With regard to the first of these questions, Whether they can be 
made of sufficient size to be of any practical use ? It is impossible 
at present to answer this question, these experiments having been 
made with only very small quantities of metal (in no case exceeding 
more than ten ounces), so that it can hardly be said that they have 
had given them a fair chance. I believe that if experiments were 
made with large quantities, say with 200 or 300 ounces of metal, one 
might obtain large crystals which, if even they were coloured, might 
be of immense value for drills and mining instruments, &c. 
Then as regards the cost of production, that would be very slight, 
indeed only the cost of producing the sugar charcoal in an 
impalpable powder, as the silver (and platinum in case of an alloy) 
is all regained from its solution with very trifling loss, so that if the 
process on a large scale were to be a success, with practice it might 
be worked with but small expense. The third question as to 
whether they can be produced transparent and with the lustre of the 
natural diamond on a large scale is one purely of experiment. I am 
under the impression that this could be done as soon as one had 
learnt by practice' just the amount of carbon necessary for the 
complete saturation of the metal and no more — it is probable that 
then these crystals might be obtained in a perfectly transparent 
condition possessing adamantine lustre — but after all it is a matter 
of experiment, and even though they were not produced of this kind 
so as to be serviceable for ornamental purposes, still if these 
