" There are but two principal channels through which the salts entering the organism with the aliments can effect their exit from the body, viz. they must either be carried off in the fwees, or in the urine. The most simple experiments show that soluble salts are car ried off by the faces only when the amount of salt contained in the fluids in the intestines is larger than that contained in the blood. If the amount of salt in these fluids is equal or inferior to that of the blood, the soluble salts are re-absorbed by the absorbing vessels of the intestinal tube, and enter the circula tion, and are then removed from the body by the urinary organs and channels. If the amount of salt contained in the intestinal tube is larger than that contained in the blood, the salts exercise a purgative action.
" If, after previous evacuation of the rec tum, a weak solution of common salt (one part of salt to sixty parts of water) be taken by means of a clyster, no second evacuation will take place : the fluid is absorbed, and all the salt is found in the urine. This experiment yields the most convincing results if ferro cyanide of potassium is substituted for com mon salt. In this case the first urine excreted after the injection of the saline solution, and frequently even after so short a time as fifteen minutes, contains so copious an amount of ferrocyanide of potassium as to yield, upon the addition of persalts of iron, a copious pre cipitate of Prussian blue.
" The influence which salts in general ex ercise upon the secretion of urine is in the highest degree worthy of attention. It is a well known fact, that a very speedy emission of urine takes place in healthy individuals after drinking fresh pump-water. If ten glasses of water of from six to eight ounces each, containing no more than nth of its amount in salts, be drunk at short intervals, an emission of urine of the usual colour will, after the lapse of about ten minutes, follow the second glass, and from eight to nine eva cuations of urine will generally occur in the course of an hour and a half. The urine in this experiment emitted in the last evacuation will be clear and colourless like pump-water, and the amount of salts it contains is little more than is contained in pump-water. There are individuals who are capable of thus im bibing from six to eight quarts of water con secutively without any inconvenience " But the case is quite different with water possessing an amount of salts equal to that of the blood ; if even as little as 1-100th part of common salt be added to pump-water, and from three to four glasses drank, no evacua tion of urine will take place, even two hours after drinking. It is almost impossible to drink
more than three glasses of this saline water, for it weighs heavily on the stomach, as if the absorbent vessels had no power of taking it up. This obviously arises from the fluid with in the channels of circulation, i. e. the blood, and the fluid without these vessels, i.e. the sa line water, not exercising any physical action upon one another, i. e. not intermixing by endosmose or exosmose.
" Water containing a larger amount o_ salts than the blood, such as common sea water, for instance, and even the weaker kinds of saline mineral waters, exercise again a dif ferent action from that of pump-water mixed with 1-100th of common salt ; not only no emission of urine takes place after the imbibi tion of such saline water, but water exudes from the circulating vessels into the intestinal tube, and, together with the saline solution, is carried off through the rectum ; purgation takes place, attended with much thirst, if the saline solution be in some measure concen trated.
" Considering that a certain amount of salts is absolutely necessary to constitute normal blood, we may deduce from these observations and experiments (which any one may easily imitate and verify upon his own person) that the physical condition of the tissues or of the bloodvessels opposes an obstacle to any in crease or decrease of the amount of salts in the blood ; and thus that the blood cannot become richer or poorer in salts beyond a cer tain limit.
" Fluids containing a larger amount of salts than the blood remain unabsorbed, and leave the organism through the rectum ; fluids con taining a smaller amount of salts than the blood enter into the circulation, absorb, and remove from the organism, through the uri nary channels, all the soluble salts and other substances which do not belong to the con stitution of the blood ; so that, finally, only those substances remain in the organism which exist in chemical combination with the con stituents of the blood, and which, therefore, are incapable of being excreted by the healthy kidneys.