324 PHILOSOPHICAL TRANSACTIONS. [aNNO 1778. 



smell, so as to render the air very noxious: he supposes this effluvia to be pure 

 phlogiston. Hence it seems that this principle is capable of rising, per se, un- 

 combined with the saline part of animal bodies, the union of which is supposed 

 to give the putrid smell. It proves Sir John Pringle's supposition, that phlo- 

 giston, when single, is imperceptible to the smell ; but it also shows it to be pes- 

 tilential. In our experiments it was devoid of smell, consequently contained no 

 mixture of volatilized acid; yet it had the common property of all putrid effluvia, 

 that of rendering common air noxious. 



Exp. 1 1. Air taken from within a privy was found in several experiments to be 

 equally good with the common atmospheric air. The result of these experiments 

 was contrary to expectation, and Dr. W. was not satisfied without making several 

 trials. Sir John Pringle observes, that the faeces humanae are perhaps in a na- 

 tural state little if at all infectious. These experiments confirm the justness of 

 his supposition. The recent excreta of a person in perfect health are here un- 

 derstood; in putrid diseases they must necessarily partake of the general state of 

 the system, and become very noxious and infectious. 



Exp. 12. The following experiments were made to discover the effects of ve- 

 getable effluvia on air. They were put into a phial of air, containing 8 ounces, 

 immediately after being gathered out of the garden; the time of standing toge- 

 ther half an hour, except in a few cases particularly noticed. 



Flowers of ulmaria, diminished it from63to52 Flowers of tree primrose, diminished it from6(itoj6 



Ten-week stocks 6"3. . 53 Antirrhinum 60. . 37 



Mignionette (iO. . 54 Leaves of sage 6l . . 55 



Calendula vulgaris 60. . 54 Thyme 6l . . 56 



French ditto 60. . 55 Mint (common) 6l. . 57 



Nasturtium indicum 60. . 55 Ditto (pepper) 6l . . 57 



Carnations 60. . 56 Parsley 6l . . 57 



It is evident from these experiments, that vegetables, when fresh and vigorous, 

 exhale a noxious matter in considerable quantity, which quickly renders common 

 air noxious. This is most remarkable in the flowers, next in the leaves, and this 

 in proportion to their firmness and texture. 



Exp. 13. In the last experiments the air only stood in contact with the vege- 

 tables half an hour; let us see here what effect a longer time of standing toge- 

 ther may have, viz. l6 hours. 



Flowers of ulmaria diminished it from 6o to 2 



Ten-week stocks 6o. . . . 1 



Leaves of sage 6 1 .... 9 



Tlie vegetables were at the end equally sweet as when first gathered and put 

 into the phial of air. These facts are very curious, interesting, and convincing. 

 It is amazing that vegetables, while fresh and free from the least degree of putres- 

 cency, should have such a noxious tendency as to spoil the air, and render it not 

 only useless but fatal to animal life, and that in so short a time. We have here 



