rOL. X.] PHILOSOPHICAL TRANSACTIONS. 239 



** forbears now to mention any further the carriage of the writer of the Trans- 

 actions in this affair :" and only adding, that if this writer of mechanics shall 

 think fit to explain what he means by it, he will certainly meet with a full 

 answer, vindicating the integrity of the editor in such a manner, that all im- 

 partial and good men shall be abundantly satisfied with it. 



Pneumatical Experiments made with the. uiir-pump. By M. Huygens and 



M. Papin* N° IIQ, p. 443. 



To mix several liquors together by means of the air-pump, two small glasses 

 were employed, one of which could enter into the other, and the least of them 

 was fastened to the hook of an iron-wire, passing through a small hole in the 

 top of the receiver, and tied close about with an eel-skin ; and the larger glass 

 set under it; and the said wire was so ordered till the recipient was exhausted. 

 Then, by means of the iron wire, the small glass was let down into the larger, 

 till the liquors they contain mixed themselves. Thus, some aquafortis was 

 poured into the upper glass, and spirit of wine into the lower, and the receiver 

 was so well exhausted of the air, that the spirit of wine boiled up with large 

 bubbles, and the aquafortis emitted some small bubbles. After both these 

 liquors were well purged of air, the upper glass was sunk into the lower, so 

 that the spirit of wine was mingled with the aquafortis; when there was yet seen 

 a very considerable ebullition. 



Now, in order to know whether the aquafortis imparted to the spirit of wine 

 some new vigour, or force, to make it bubble ; some aquafortis was mixed with 

 spirit of wine, without the receiver; the quantity of the former being somewhat 

 more than that of the latter. This mixture being put in vacuo, instead of boil- 

 ing up more strongly than the spirit of wine, as it was thought it would have 

 done, it only cast up some few bubbles: which showed that the ebullition which 

 was seen when they were mixed within the vacuum is of the same nature with all 

 those that are made of acids and alcalies. For in the very instant of mixture, 

 they make great ebullitions, but soon after they destroy each other, and lose the 

 properties they had before. It is also probable, that the aquafortis and the 

 spirit of wine would boil always when they are mingled, were it not that the 

 pressure of the air prevents this ebullition from being sensible, and appears only 

 when that pressure is removed. 



It was also found, that the solution of common salt boils when mixed in vacuo 



* This was Nicholas Papin, author of the celebrated digester, for making soup of bones, and of 

 some ingenious books, as well as several papers inserted in the Philosophical Transactions, volume 

 10, 15, l6, 24. His uncle Nicholas, and his cousin Isaac, were also learned French philosophers. 



