350 CHEM ICO- PHYSIOLOGICAL CONSIDERATIONS ON 
we gain in forcing doses of diuretic salts; and that it is, on the 
contrary, better to divide them, and repeat them as often as 
required. 
When we administer them in a state of dilution, endosmose and 
absorption rapidly carry the salts into the circulation ; whence they 
soon pass into the urinary organs, and produce a potent diuresis. 
This is a point well established in the history of alkaline diuretics. 
But how do the salts produce this extraordinary activity in the 
secretion and excretion of urine ? On this point science is less 
positive, and admits of divers hypotheses more or less probable. 
If the urinary apparatus is designed to maintain the watery 
constituents of the blood in proper proportion, we may sav as 
much of the other components of this nutritive fluid, and especially 
of its saline materials. Therefore, if salts penetrate into the blood 
in quantity in excess of the requirements of the system, the kid- 
neys separate them by little and little from the fluid, until it retains 
no more than its normal proportion of them. Such is the phy- 
siological explanation given of the diuretic action of the alkaline 
salts. 
Chemistry, however, opens to us another interpretation of this. 
M. Chevreul was the first to establish that alkaline substances 
possessed the property of facilitating the chemical metamorphoses 
of the nutritive principles introduced into the blood through ab- 
sorption, and submitted to the combustible influence of the expired 
air. Experience has since completely confirmed the exactitude of 
this theory ; and the essays of Messrs. Laveran and Millon leave 
not the slightest doubt on this head. They have witnessed con- 
stantly the augmented proportion of urea in alkaline urine ; evi- 
dently shewing that the alkaline ingredients facilitated the organic 
combustion, and accelerated the transformation of the tissues into 
refuse matters to be thrown off with the urine as henceforth 
unsuitable for nutrition. Such is the chief action assigned by 
chemistry to these agents ; but it is not the only one. There is 
another equally important, which must not be omitted, on account 
of its likelihood to lead to some practical remarks. 
The organisable elements of the blood, fibrin, albumen, and 
caseine, are very soluble in alkaline fluids, and owe their state of 
solution or division in the blood to salts of this nature contained in 
that fluid. The natural quantity of such salts is in the proportion 
necessary for the fluidity of the blood, beyond which normal ratio 
it does not pass. The organisable elements are dissolved or di- 
vided in such manner as to pass without difficulty through the 
smallest passages of the organism, without detriment either to their 
plastic properties or to their coagulability. If we now suppose that 
the proportion of the alkaline principles of the blood become aug- 
mented, we ought to admit that their state of division, of tenuity 
