362 CHEMISTR V OF THE DIGESTIVE PROCESSES. 
perfect diffusion 1 apparatus ; on the removal of the hydrochloric acid, 
fresh acid is formed by further mass action on the chlorides. The 
kidneys or sweat glands probably do not so secrete hydrochloric acid, 
because they are not such perfect diffusion arrangements as the gastric 
glands, and cannot bring about such a molecular separation as the latter. 
Objections to Maly's theory. — 1. Modern work has shown that the 
alkaline reaction of theoretically acid salts is probably due to a hydro- 
lysis taking place on solution. Thus on dissolving sodium bicarbonate 
there are formed sodic hydrate and carl ionic acid (XaHC0 3 + H. 2 0=NaOH 
+ H 2 C0 3 ); and the sodic hydrate being a powerful base, and the car- 
bonic acid a weak acid, one equivalent of the base more than balances 
two of the acid, and the reaction is alkaline. On the other hand, when 
acid potassium sulphate is dissolved, there is one equivalent in solution 
of a strong base, and two equivalents of a strong acid, and the reaction 
is acid. Such an hydrolysis of phosphates of the alkalies also takes 
place. Trisodic phosphate yields an equivalent of base to one of acid, 
and the reaction is intensely alkaline ; disodic phosphate yields only two 
equivalents of base to three of acid, but the reaction is still alkaline; 
while monosodic phosphate yields but one equivalent of base to three of 
acid, and at last the react loe is acid. A mixture of mono- and disodic 
phosphates in proper proportion would be neutral. In fact, after these 
salts are dissolved, they no longer exist as such, but there are present in 
solution bases ami acids in certain concentrations, and the reaction of the 
solution will depend on which of these acts most strongly on the in- 
dicator. Now the hydrolysing effect on the neutral salts, chlorides, etc. 
(if such are also present in solution), of these so-called acid salts must 
closely resemble their effect on the indicator. 
Whether there will he a tendency to formation of hydrochloric acid 
or not from sodium chloride, will lie determined by whether the attraction 
of the acids (phosphoric and carbonic) for the base is greater or loss 
than the attraction of the liases for the hydrochloric acid." The reaction 
of the solution of phosphates and carbonates in the plasma is alkaline, 
which shows that the latter is the case, and that, therefore, there will be 
no hydrochloric acid formed. 
2. The continuous formation of hydrochloric acid by a reaction 
between disodic phosphate and calcium chloride is impossible, because it 
necessitates the formation of insoluble tricalcic phosphate, and as the 
supply of calcium chloride is small, must soon stop. 
■">. Even if it he admitted that there are traces of hydrochloric acid 
in the blood, there is no reason, if the process be purely one of diffusion, 
why it should not go on continuously. This it does not do, but ceases 
when digestion is not going on, and when digestion begins is secreted in 
such amount that no mere physical diffusion could bring it through the 
epithelial cells fast enough : not to speak of separating it from a fluid 
in which it is supposed fco he present in traces only. 2 
1 By a perfect diffusion apparatus (vollkommener Diffimtms-apparat) Maly seems to 
mean here semipermeable membrane ; that is, an arrangement permeable to the hydrochloric 
arid and not to the other dissolved substances. 
2 Gastric juice contains at least 2 parts per 1000 of hydrochloric acid: the amount of 
hydrochloric acid formed by mass action in a solution of b' parts per 1000 of sodium 
chloride, and a still smaller quantity of monosodium phosphates, no one lias ever attempted 
to measure, but it must be many thousand times less than this ; so that not only must the 
hydrochloric acid diffuse with a tremendous velocity, but it nlust get infinitely more con- 
centrated in the process of diffusion, which, under purely physical conditions, so far as 
we know them, is an utter impossibility. 
