Application of the Electrotype Process in Organic Analysis. 439 
blood-cells, And as a larval state in the Batrachia, &c. is in- 
dicated by a retention of the gills, is it surprising that we find 
their blood-corpuscles large in proportion to the length of 
time during which they retain the gills ? 
7. I cannot doubt that a law of the kind now mentioned— 
progressive diminution in the size of cells—is general in its 
operation; and if so it may regulate the magnitude of the 
corpuscles in other blood. 
LXXIV.: On an application of the Electrotype Process, in 
conducting Organic Analysis. By Ropert Marie, Ph. D. 
To Richard Phillips, Esq. 
Dear Sir, 
AN application of the electrotype process has been made 
~-*% by me, which appears of some value to those engaged in 
the pursuit of organic analysis; I therefore hope a brief no- 
tice of it may not be out of place in the Philosophical Ma- 
gazine. When very high temperatures are required to effect 
or complete difficult combustions with oxide of copper or 
chromate of lead, as in the determination of carbon in cer- 
tain varieties of cast iron (which indeed suggested the appli- 
cation to me), the glass tube is liable to soften and get dis- 
torted, though of Bohemian glass, and it has been usual to 
cover it by lapping a spiral strip of thin copper round the 
tube. This however is never in close contact, even when 
cold, and the tube is liable to be broken either in the lapping 
or during the combustion. 
The method I have now to mention as a substitute for this, 
consists in brushing over the outside of the combustion tube 
with a very thin coat of Canada balsam and turpentine, dust- 
ing it over with fine powder of plumbago which adheres 
thereto, connecting one end of the combustion tube with a 
copper wire, and plunging the whole into a cell of sulphate of 
copper in the common electrotype arrangement, In a few 
hours the whole exterior of the tube is found covered with a 
perfect, close and coherent jacket or tube of copper, and may 
now be at once put into use. 
The copper covering adheres so close to the glass tube, and 
is so completely itself an air-¢ight combustion tube of copper, 
that should the glass tube crack in the combustion it is of 
little importance. 
The film of Canada balsam, between is so indefinitely thin 
that its decomposition has no injurious effect. A combustion 
tube of 18 inches long is only increased in weight about ;4,th 
of a grain by this coating, when dry (without the plumbago 
