320 PHILOSOPHICAL TRANSACTIONS. [aNNO I766. 



that this factitious air should seem to be rather heavier than air from zinc ; but 

 the quantity tried was too small to afford any great degree of certainty. 



N. B. The weight of 4540 grain measures of inflammable air, is tYt grains, 

 and the weight of the same quantity of common air is 5-,\- grains. 



On the whole it seems that this sort of inflammable air is nearly of the same 

 kind as that produced from metals. It should seem however, either to be not 

 exactly the same, or else to be mixed with some air heavier than it, and which 

 has in some degree the property of extinguishing flame, like fixed air. 



The weight of the inflammable air discharged from the gravy appears to be 

 about one grain ; which is but a small part of the loss of weight which it suf- 

 fered in putrefaction. Part of the remainder, according to Mr. M'Bride's expe- 

 riments, must have been fixed air. But the colour and smell, communicated to 

 the soap leys, shew that it must have discharged some other substance, besides 

 fixed and inflammable air. Raw meat also yields inflammable air by putrefaction, 

 but not in near so great a quantity, in proportion to the loss of weight which it 

 suffers, as gravy does. Four ounces of raw meat mixed with water, and treated 

 in the same manner as the gravy, lost about 100 grains in putrefaction ; but it 

 yielded hardly more inflammable air than the gravy. This air seemed of the same 

 kind as the former ; but, as the experiments were not tried so exactly, they are 

 not set down. 



Mr. C. endeavoured to collect in the same maimer the air discharged from 

 bread and water by fermentation, but he could not get it to ferment, or yield any 

 sensible quantity of air; though he added a little putrid gravy by way of ferment. 



XX. A further Account of the Polish Cochineal, from Dr. Wolfe, of Warsaw, 



p. 184. 



In the Liv* volume of the Phil. Trans, are published two curious papers, 

 from Dr. Wolfe, of "Warsaw, describing the Polish cochineal, the plants on 

 whose roots it is found, the manner of collecting and curing it, the method of 

 dying with it, and also the doctor s own experiments on these curious insects. 



Since that time, the doctor has been very industrious in breeding and observ- 

 ing these insects, and has thus discovered the male fly, about which he was be- 

 fore uncertain ; and has sent to Mr. Baker an elegant picture of it, painted from 

 the life in its natural colours, and also of the young female just crept from the 

 egg, both in their natural size, and as magnified by glasses ; together with a 

 drawing and description of the polygonum minus of Casper Bauhine, or scleran 

 thus perennis of Linnaeus, which is the plant, adhering to the roots of which 

 this insect is chiefly found in Podolia and the Ukrain. 



* Page 110 of this vol. of these Abridgments. 



