URINE AND ITU CONSTITUENTS. 



743 



ends, but sometimes also in star-shaped, feathery crystals, due to the 

 partial dissolving of the first type. These crystals are most abundant 

 in alkaline urine, but are also present in faintly acid urines. They 

 dissolve in acetic acid. 



(b) In alkaline urine. Ammonium-magnesium phosphate (vide supra). 



FIG. 79. 



Ammonium urate crystals. (C. E. Simon.) 



Calcium and magnesium phosphates. These are basic phosphates. 

 They form the commonest sediment in alkaline urine, are amorphous, 

 dissolve with acetic acid, but not with heat. 



FIG. 80. 



y- 



Crystals of leucine (different forms). (Crystals of creatinine-zinc chloride resemble the 

 leucine crystals depicted at a.) The crystals figured to the right consist of comparativelj 

 impure leucine. (Charles.) 



(c) In ammoniacal urine. Ammonium-magnesium phosphate (vide 



supra). 



Ammonium urate is found, generally associated with amorphous or 

 crystalline phosphates, in urine which has become ammoniacal. 

 crystalline globules are generally covered with spinous excrescences, 

 which give them the characteristic "thorn-apple" appearance, and 

 have a yellow color. They are soluble in acetic acid. 



