[ 3 20 3 
than can at all times be fafely taken away ; and Rain- 
Water, with which the fpecihc Gravity of the Blood 
is compared, I have found, by repeated Experiments, 
to lofe about Parts of a Grain for each Degree 
of Heat by Fahrenheit's Thermometer ; and Oil of 
Turpentine, in which the Craftf amentum is weigh’d, 
Iofes much more of its fpecific Gravity. 
If I can poflibly obtain the fame kind of Inftru- 
ments which Dr, Eangrijh ufed, I would likewife 
take the Cohefion of the Blood, and analyfe it and 
the Urine in different Difeafes, &c. but the Diffi- 
culty of getting exaft Inhruments is very great. 
That you may enjoy long Life, and perfect Health, 
to improve that Science in which you are fo worthily 
exercifed, is the fincere With of, 
A S the Quantity of Ingefta varied con in 
* almoft every Month, the Increase and Decreafe 
of the fevcral Excreta , as they were influenced by that 
Conftitution of the Air, which is exhibited in TAIL 
IV. p. 506, 507. Tran£. N°. 470. cannot plainly appear. 
I have therefore calculated the following Table from 
that, fuppofing the mean Ingefta of each Month to be 
3000 Ounces, which is equal to 100 Ounces each Day ; 
and that the feveral Excreta were evacuated in the fame 
SIR, 
Tour moft obliged , 
and moft humble Servant , 
Ratio 
