SODIUM AND POTASSIUM SULPHATES. 53 



blood, the lymph, the aqueous humor, milk, saliva, mucus, the perspira- 

 tion, and the urine. They are usually, however, in small quantity, as 

 compared with other saline matters. In the blood and the lymph, they 

 are much less abundant than either the chlorides, phosphates, or car- 

 bonates. In the milk and the saliva, there is hardly more than a trace 

 of them ; and they have not been found at all in the bones, the gastric 

 juice, the bile, or the pancreatic juice. They are most abundant in the 

 urine, where they amount to rather more than one-half the quantity of the 

 phosphates, and they are found also, in small proportion, in the feces. 



The sulphates are introduced into the body, to some extent, with the 

 food and drink. They are to be found, in minute quantity, in muscular 

 flesh and in the yolk of egg. They exist also in certain vegetable pro- 

 ducts, such as the cereal grains, fruits, and tuberous roots, where they are 

 much less abundant than the phosphates, though often more so than the 

 chlorides. Spring and river water, as used for drink, usually contains 

 sulphates, including sulphate of lime, varying in amount, according to 

 the tables given by Payen, 1 from .003 to .06 per thousand parts. In 

 the water of the Croton River, with which the city of New York is sup- 

 plied, they amount, as shown by the analyses of Prof. Chandler, 2 to a 

 little more than .007 per thousand parts. 



Beside the sulphates, however, introduced with the food and drink, a 

 certain amount of sulphuric acid originates within the body by oxida- 

 tion, in a mode analogous to that already described for phosphoric acid. 

 The albuminous substances, which form so important a part of the solid 

 food, contain sulphur as one of their constituent elements, and a con- 

 siderable quantity of this substance is accordingly introduced daily into 

 the system in the form of organic combination. The entire quantity of 

 sulphur, thus forming part of the organic matters of the body of a man 

 of medium size, amounts, according to Payen, 3 to about 110 grammes ; 

 and at least 1 gramme must be taken daity with the albuminous ingre- 

 dients of the food. A portion of these substances is expelled by the 

 daily exfoliation of the hair, nails, and epidermis; but no such sul- 

 phurous organic compound is discharged by the urine and feces except 

 in insignificant quantity. On the other hand, the sulphates are compar- 

 atively abundant in the excretions. While they are to be found in the 

 blood only in the proportion of 0.28 per thousand, they exist in the 

 urine in the proportion of from 3.00 to 7.00 parts per thousand, 4 and are 

 discharged by this channel to the amount of about 4 grammes per day. 



These facts indicate that a notable quantity of sulphuric acid is con- 

 stantly formed in the body, during the decomposition of albuminous 

 matters, by oxidation of their sulphur. This is confirmed by the fact 

 that the quantity of sulphuric acid in the sulphates eliminated by the 

 kidneys is perceptibly increased by the use of a flesh diet, and also by 



1 Substances Alimentaires. Paris, 1865, p. 436. 



2 Lecture on Water. Transactions of the American Institute for 1870-71. 

 8 Substances Alimentaires. Paris, 1865, p. 68. 



4 Robin, LeQons sur les Humeurs. Paris, 1874, p. 770. 



