PHYSICAL AND LITERARY. 351 



None of the balls mentioned in thefe 

 four laft hiftories have any tartarous cruft, 

 but they and all the other cut ones have the 

 appearance of being compofed of jlrata 

 furrounding the nucleus, their colour dif- 

 fering in lliades from a dark rufty to a pale 

 afhy colour. Their fubftance, except vvhere 

 there is tartarous cruft, refembles a fine hat 

 or chamois-leather when cut. 



Hijl. 7. In the coUedtion of curiofities 

 kept by the Surgeons of this place, there 

 is a ball taken out of the ftomach of 

 a horfe, which is nearly fpherical, and 

 nineteen inches in circumference. Its 

 furface has fomething of the mulberry 

 form, Deing compofed of a great number 

 of hemifpherical knobs, about a quarter 

 of an inch diameter contiguous to each 

 other. Their outward (liell looks like a 

 thin cruft of fandy clay ; but within this 

 the fubftance has the fame matted appear- 

 ance as the human concretions have. 



Hi/i. 8. Balls are alfo frequently form- 

 ed in the ftomachs of cows. Three of 

 them which were given to me, are al- 

 moft exa<5t fpheres of a black colour, com- 

 pofed 



