The following table of analyses of vesical calculus of the horse and ass is given by Furstenberg: -

Horse.

ASS.

Yellowish White.

Brown.

Brown.

White Hard.

Sedimentary Form.

Yellowish

White.

Yellowish Brown.

White

Hard.

Specific gravity ......

2.231

2.104

2.017

2.245

2.076

2.213

1.767

2.257

Carbonate of lime ...

87.10

83.25

61.55

85.03

84.30

69.90

67.75

80.3

Carbonate of magnesia

3.63

5.73

8.97

3.62

8.34

6.75

9.93

15.5

Oxalate of lime ......

2.10

2.60

17.57

...

4.44

10.25

Trace.

Phosphate of lime ..

...

...

4.32

5.81

...

4.37

...

...

Ammonio-phosphatel of magnesia ......

...

...

...

...

...

...

...

...

Silicic acid ...........

..

..

...

...

...

...

...

...

Uric acid............

...

...

...

...

...

...

...

...

Organic Matter...

5.45

6.67

5.95

4.21

5.95

12.75

10.95

2.9

Water and loss

1.72

1.75

1.64

1.33

1.41

1.79

112

1.3

Trace.

100.00

100.00

100.00

100.00

100.00

100.00

100.00

100.0

Calculi, it will be seen, are composed of earthy salts in combination with a greater or less amount of organic matter. As shown by reference to the above analyses, carbonate of lime constitutes over 80 per cent ot the whole. Vesical calculi in the horse are strikingly uniform in composition, and in this respect contrast greatly with similar formations in omnivorous man, in whom they are also more frequent. In him the urine contains a greater number and variety of crystallizable substances, several of which, both separately and in combination with others, assume the form of stone. Hence we have calculi of uric acid, urates of soda, ammonia, and lime, as well as others of calcic acetate, triple phosphate, and various combinations of these renal salts.