584 PHILOSOPHICAL TRANSACTIONS' [aNNO 16q3. 



it does not come up to the standard of volatility, and is really no volatile salt, 

 «s will be made appear, if you take this supposed volatile salt, and distil it in a 

 retort, or head and body, with common water, the water will ascend in such a 

 degree of fire where the salt will not ; for you must increase the fire consider- 

 ably, to make it rise after the water is evaporated and has left the dry salt at 

 the bottom. This made me inquire further into the properties of this salt, 

 which did not at all correspond with volatile salts, for all true volatile salts are 

 alkalies ; but on the contrary would ferment with them, and quite destroy the 

 property of true volatile salts, by bringing them to a dull insipid salt, which 

 some call sal neutrum ; and also, by fixing their volatile nature, quite destroy 

 their spirituous and stimulating smell, by virtue of which they have been always 

 deservedly esteemed such excellent cephalic medicines. Therefore, examining 

 this salt yet a little further, you will plainly prove it to be an acid, that corrodes 

 iron, turns syrup of July-fiowers green, destroys the tincture of lignum ne- 

 phriticum, and does not ferment with common acids ; so that it plainly belongs 

 to the tribe of acid^,* and should be struck out of the catalogue of volatile 

 salts ; and perhaps out of the number of specific cephalics, and rather be de- 

 graded among the diuretics, and even in that rank to have but an inferior 

 station ; for it seems to me to be but a dull medicine, and more valuable for 

 its price than great virtue, especially if quite divested of all its oil, in which 

 the great cephalic and cordial virtue must needs be owned to consist. 



Corol. 3. — Volatile salts are very powerful in extracting tinctures, and parti- 

 cularly in heightening those colours which are disposed to be red ; for though 

 spirit of wine be a very general menstruum, and draws a very deep tincture from 

 cochineal, yet it has been often observed, that if we put to this tincture, when 

 highest, a small proportion of volatile salt, it will be advanced to a great, even 

 to a double degree. Thus I have observed it to heighten the colour of arterial 

 blood ; and, which is very curious, if you dissolve it in your blood whilst 

 bleeding at a vein, that blood will become very florid, and like the arterial. 

 Therefore, since nitrous salts produce none of these tinging effects, this corol- 

 lary seems much to favour the notion, that the effects of the air upon the 

 blood may be due to such salts as are of a volatile alkalisate nature, -f- 



CoroL 4. — Contagious diseases are communicated by the air inspired at the 

 lungs ; which seems more probable then what Dr. Needham and others have 

 endeavoured to make out ; in attributing it to the air taken in with our food, 

 because of the smallness of the quantity, if compared with what is communi- 



• And is accordingly now referred to its proper class in the modern systems of chemistry, under 

 the denomination of succinic acid. 



f Here Dr. S. has been betrayed into an error by reasoning from analogy. 



