VOL. XXVI.] PHILOSOPHICAL TRANSACTIONS. 3QQ 



per barrel, according to its goodness: the best sort is that which is freest from 

 clay and dirt, which are commonly mixed with it: and the way of trying it, is 

 by washing it in salt water, which will cleanse it. The Arabs and Turks call it 

 cotter mija. N. B. A barrel is 420lb. 



The Practice of Purging and Vomiting Medicines. Inscribed to Dr. Gar thy* 

 F. R. S. By JV. Cockburn, M. D. N° 314, p. 46. 



By my solution of the problem (Phil. Trans. N° 303) for determining the 

 proper doses of purging and vomiting medicines, in all their cases, it is manifest 

 in general, 1. That these medicines operate either by mixing with the blood, or 

 by stimulating the stomach and guts. 2. That their operation is more or less, 

 according to the quantity and thickness of blood ; that is, a greater quantity, 

 and the thickest blood require the greatest doses: and 3. That when the quan- 

 tities of blood are the same, the doses of purging and vomiting medicines are 

 in a duplicate ratio of the thickness of the blood: as also, that in every case, 

 these doses must be in a proportion compounded of the quantity of blood and 

 the squares of its thickness. 



Now, since the operations of purgative and vomitive medicines depend so 

 much on the quantity and viscidity of the blood, which have not hitherto 

 been duly considered ; it is no wonder that the practice of physic, in these eva- 

 cuations, has been so uncertain, and that the most expert physicians, from their 

 most accurate observations, could never determine the true doses of medicines, 

 which alter so much according to the various subjects they work upon ; as they 

 are not acquainted with the true method of determining either the quantity of 

 the blood, or the degrees of its thickness. 



Now, as experience is equally the foundation and touchstone of all reason- 

 ing in physic, we will here submit the solution to common observations ; and 

 try whether every thing, proposed , in it, does not exactly answer matters of 

 fact, and the visible operations of nature. First then, it plainly follows, that 

 these medicines always purge best, and most constantly, in a liquid form ; be- 

 cause they are more easily conveyed into the blood ; and can stimulate more 

 parts; whatever may be the way that purges and vomits work, or whatever their 



* The name of Dr. Samuel Garth has been perpetuated by a satirical poem, entitled ;the Dispen- 

 sary, written (as one of his biographers has remarked) in defence " of charity against the, intrigues 

 of interest, and of regular learning against licentious usurpation of medical authorit}." He was a 

 native of Yorkshire, and took his degree of M. D. at Cambridge in 169I3 after which he removed 

 to London, where he soon got into great practice; particularly among the Whig party, of which he 

 w^s a zealous supporter. On the accession of Greorge I. he. received the honour of knighthood, and 

 was appointed physician to the king, and physicjwn generai,|to the army. He died in ^7jV<?.»«j > Jiuy 



