470 
POPULAR SCIENCE REVIEW. 
to the column of mercury, the elevation and depression of this latter throw 
shadows on a revolving sheet of photographic paper and are thus re- 
corded. 
The Coagulation of the Blood. — With a degree of moral courage which 
we fear few of our savants would venture to show, Dr. Richardson has with- 
drawn his theory of the coagulation of the "blood. At the meeting of the 
British Association he announced that recent research showed the ammonia 
hypothesis to be no longer tenable, and he therefore begged to withdraw it. 
Experiments which he had lately made on the influence of extremes of heat 
and cold on albuminous and fibrinous fluids, have shown to him that the 
process of coagulation in these fluids is due to a communication of caloric 
force to them, and to a physical or molecular change, determined by the 
condition of their constituent water. Thus all substances which possess the 
power of holding blood in the fluid condition, through fixed alkalies, various 
soluble salts, and volatile alkali, in every respect act after the manner of cold. 
They render latent so much heat, and in the absence of that heat the fibrine 
remains fluid. In the opposite sense, every substance which combines with 
water and produces condensation, with liberation of heat, quickens coagula- 
tion. The direct effects of heat and cold illustrate the same truth, and 
upon these facts turn the differences of coagulation in animals of different 
temperatures. Those of our philosophers who work for reputation alone 
(not a few), may think a recantation like that of Dr. Richardson’s rather a 
perilous proceeding. To some small minds it may seem so. We venture to 
believe, however, that the step Dr. Richardson has taken redounds in the 
highest manner to his credit, and we believe that it will only add another 
honour to a name which has always been associated with that honest pursuit 
of science which results from an earnest desire to discover truth. 
VulpiarHs Experiments on the Heart. — M. Vulpian lately described to the 
Societe Philomathique his curious experiments on dogs. These experiments 
were conducted with a view to ascertain the mode of origin and cause of 
inflammation of the heart. In each case the animal was laid on its back, and 
the flesh having been opened with a scalpel just over the point at which the 
apex of the heart strikes the chest, a trochar was driven into the cavity of 
the heart. This being effected, small portions of copper wire, pieces of wood, 
and so forth, were introduced into the heart, and the instrument was then 
removed. The animals being then released, some of them died and some 
recovered. Post-mortem examination showed that in both cases the wires 
had penetrated the substance of the heart, and in others had been forced by 
the blood-current into the arteries, in some of which their further passage 
was obstructed. In one instance, the copper wire lodged in the subclavian 
artery, and produced a well-marked endo-arteritis, consisting of a softening 
of the walls, fissure of the inner membrane, and a sort of vegetation. 
— Report of meeting of the Societe Philomathique , July 6. 
The cause of Osteomalacea is thus explained by M. Drivon in a paper 
published in the Gazette Medicate de Lyon , for July : — The diseased bones 
contain lactates, and probably lactic acid in considerable quantity ; these 
help to dissolve the earthy carbonates and phosphates, which being then 
resorbed, produce the softened condition characteristic of this malady. 
The Poison of the Spotted Salamander. — The poisonous substance of the 
