YOL. v.] PHILOSOPHICAL TRANSACTIONS. 473 



Galileus and others ; yet he thinks he has handled it more fully, more distinctly, 

 and easily. 



III. The Natural History of Nitre, or, a Philosophical Discourse of the Na- 

 ture, Generation, Place, and Artificial Extraction of Nitre, with its Virtues 

 and Uses, by William Clarke. London, 1670, in 8vo. 



There is nothing in this treatise worthy the attention of modern chemists. 



New Pncumatical Experiments about Respiration, by tJie Honourable 

 Robert Boyle. N" 62, />. 201 1 . 



The First Title. 

 Observations on the lasting of Ducks included in the Exhausted Receiver. 



Nature having, as zoologists teach us, furnished ducks and other water-fowl 

 with a peculiar structure of some vessels about the heart, to enable them, when 

 they have occasion to dive, to forbear for a while respiring under water with- 

 out prejudice; I thought it worth the trial, whether such birds would much 

 better than other animals endure the absence of the air in our exhausted re- 

 ceiver. The accounts of which trials were registered as follows. 



Exp. I. — ^We put a full grown duck into a receiver, of which she filled a 

 third part or somewhat more, but was not able to stand in an easy posture in 

 it; then pumping out the air, though she seemed at first to continue well some- 

 what longer than a hen in her condition would have done ; yet within the space 

 of one minute she appeared much discomposed, and between that and the 

 second minute, her struggling and convulsive motions increased so much, tiiat 

 her head also hanging carelessly down, she seemed to be just at the point of 

 death ; from which we presently rescued her by letting in the air upon her: So 

 that this duck being reduced in our receiver to a gasping condition within less 

 than two minutes, it did not appear that she was able to hold out con- 

 siderably longer than a hen, or other bird not aquatic, might have done : and 

 to manifest, that it was not closeness and narrowness of the vessel, in reference 

 to so bulky an animal, that produced in the subject of our trial the great and 

 sudden change above recited, we ^oon after included the same bird in the same 

 receiver, and having by a special way cemented it on very close, we suffered 

 her to stay thus shut up with the air for five times as long as formerly, without 

 perceiving her to be discomposed; and she would probably have continued 

 longer in the same condition, if we had tried it. 



Exp. II. — Having procured a duckling, that was yet callow, we conveyed her 

 into the same receiver wherein the former had been included, and observed, 

 that, though for a while she appeared not much disquieted, whilst the air was 



VOL. I. 3 O 



