On the Operation of Medicines. 1 1 1 



to it. Perhaps, with equal reafon, it might be 

 prefumed, by one ignorant of chemiftry, that/^/ 

 martis contains no iron, becaufe it is not afted 

 upon by the load-ftone. 



With the foregoing obfervation of Dr. Wright, 

 I lliall contraft thofe made by the celebrated 

 Dr. Miifgrave, which are alfo recorded in the 

 annals of the Royal Society. " I injefted," fays 

 he," into the Jejunum of a dpg, that had, for a 

 *' day before, but little meat, about twelve 

 **'ounces of a folution of indigo in fountain 

 *' water, and after three hours opening the dog 

 " a fecond time, I obferved feveral of the lac- 

 *' teals of a bluifii colour, which, on ftretching 

 ^' the mefentery, did feveral times difappear, 

 " but was mod eafily difcerned when the me- 

 ** fentery lay loofe, an argument that the bluifh 

 ** liquor was not properly of the veffels, but of 

 *' the liquors contained in it. A few days after 

 *' this, repeating the experiment in another com- 

 *' pany, with the folution of ftone blue, in foun- 

 " tain water, and on a dog that had been kept 

 " fafting thirty-fix hours, I faw feveral of the 

 " ladleals become of a perfeft blue colour within 

 " very few minutes after the injeftion. For they 

 " appeared before I could few up the gut. 



*' About the beginning of March following:, 



" having kept a fpaniel fafting thirty-fix hours, 



" and then fyringing a pint of deep decoftion of 



" ftone blue, with common water, into one of 



P 2 '' the 



