358 POISONS, CONTAGIONS, MIASMS. 



cause every part of the organism with which they come in con- 

 tact absorbs a certain quantity of them. 



The composition of the salts has nothing to do with their pur- 

 gative action ; it is quite a matter of indifference as far as the 

 mere production of this action is concerned (not as to its inten- 

 sity), whether the base be potash or soda, or in many cases lime 

 and magnesia ; and whether the acid be phosphoric, sulphuric, 

 nitric, or hydrochloric. 



If we drink, fasting, a glass of common spring water every 

 ten minutes, a strong diuretic action becomes apparent, the 

 quantity of salts in the water being much less than that in the 

 blood . 



When the second glass is taken, a quantity of urine is elimi- 

 nated, the weight and volume of which corresponds nearly to 

 that of the first glass ; and by drinking twenty successive 

 glasses of water, nineteen evacuations of urine take place, the 

 last of which is colorless, and scarcely differs in its amount of 

 saline ingredients from the spring water itself. 



When the same experiment is made with a water contain- 

 ing exactly the amount of salts as in blood ( j to 1 per cent, 

 of common salt for example), a separation of urine is not 

 effected, and it becomes almost impossible to drink more 

 than three glasses of such water. A sensation of fulness 

 in the stomach, of pressure and weight, seems to show that 

 water containing an equal amount of saline ingredients as blood, 

 requires a much longer time to be taken up by the blood- 

 vessels. 



When the water taken contains a larger amount of salts 

 than that existing in blood, a more or less active purgative 

 action ensues. Hence, we see that three kinds of action take 

 place, according to the quantities of salt existing in the water. 



Besides these salts, the action of which does not depend upon 

 their power of entering into combination with the component 

 parts of the organism, there is a large class of others which, 

 when introduced into the living body, effect changes of a very 

 different kind, and produce diseases or death, according to the 

 nature of these changes, without, effecting a visible lesion of any 

 organs. 



