ELEMENTARY CHEMICAL PHYSIOLOGY 265 



N.-rich diet. N.-poor diet. 



Volume of urine 1,170 c.c. 385 c.c. 



Total nitrogen 16-8 grm. 3-60 grm. 



Total SO 3 . . 3-64 grm. 0-76 grm. 



Inorganic SO 3 3-27 grm. = 90-0% of total S. 046 grm. =60-5% of total S. 



Ethereal SO 3 . 0-19grm. = 5-2% 0-10 grm. =13-2% 



Neutral SO S . 0-18 grm. = 4-8% 0-20 grm. =26-3% 



The ethereal sulphates cannot, as has been supposed, derive their source 

 entirely from the aromatic bodies formed in the intestine by micro-organismal 

 growth. When this is excessive, or when there is obstruction in the small 

 intestine so that an excessive amount of these aromatic bodies is absorbed, an 

 increase no doubt occurs in the ethereal sulphate excretion, but this increase 

 can be no reliable index of intestinal putrefaction, since the relative ethereal 

 sulphate excretion becomes greater when the diet contains little or no protein. 

 Practically the only source of sulphur intake by the food is in proteins. Sul- 

 phates are not taken unless for medicinal purposes, because of their disagreeable 

 taste. The sulphur excretion by the urine is therefore a measure of protein 

 catabolism in the organism. 



Urinary Deposits 



Normal urine is quite clear when it is passed, but, on standing 

 some time, a sediment usually separates out, and this varies some- 

 what under different conditions. 



Acid Urine from a healthy person may deposit the following : 



1. Urates (see p. 259). The sediment has a chalky appearance 

 and is usually tinged reddish by uroerythrin. It disappears on 

 warming the urine. Examined microscopically, it is generally 

 amorphous, but may show a crystalline structure, usually as needles, 

 or as balls with spines projecting from them (Fig. 187). It is 

 composed mainly of sodium urate. 



2. Uric Acid. It appears as a cayenne pepper-like sediment, and 

 has a definite crystalline appearance under the microscope (Fig. 186). 

 The crystals may vary much in shape, but are always large and 

 tinged a reddish colour. The most usual shapes for the crystals to 

 assume are " sheaves," " whetstones," " rhombic tables," and 

 sometimes " dumb-bells." The presence of the crystals does not 

 necessarily indicate an increased excretion of uric acid, but depends 

 on the concentration and acidity of the urine. 



3. Calcium Oxalate. This is usually a scanty deposit, adhering 

 to irregularities on the surface of the glass of the urine jar, or forming 

 a glistening layer on the top of the mucous deposit that settles at the 

 bottom. 



The crystals are insoluble in acetic acid. This reaction 

 distinguishes them from phosphates or carbonates. They are also 

 insoluble in ammonia, and are thus distinguished from urates. 



Microscopically they are seen to be very small octahedra, often 

 flattened along one axis, so that they appear like squares with 

 diagonal lines (hence called " envelope " crystals, Fig. 190). 



Acid urine from a person suffering from disease, or during the 

 administration of certain drugs, may deposit : 



