374 PHILOSOPHICAL TRANSACTIONS. [aNNO l66g. 



IV. An Answer to the Hydrologia Chymica of W. Sympson ; by R. Wittie, 

 M. D. 8vo. 1669. 



We did not think our readers would wish to be detained with an analysis of 

 the hydrologia chymica (mentioned at p. 303 of our Abridgement) ; much less 

 do we think they would be interested by a detail of the particulars in this reply. 



The Weight of Water in Water with ordinary Balances and Weights. 

 By Mr. Boyle. N" 50, p. 1001. 



A glass bubble, of about the size of a puUet's-egg, was purposely blown at 

 the flame of a lamp, with a somewhat long stem turned up at the end, that it 

 might the more conveniently be broken off. This bubble being well heated to 

 rarefy the air, and thereby drive out a good part of it, was nimbly sealed at the 

 end, and by the help of the figure of the stem was by a convenient weight of 

 lead depressed under water, the lead and glass being tied by a string to one 

 scale of a good balance, putting into the other scale as much weight as sufficed 

 to counterpoise the bubble, as it hung freely in the midst of the water. Then 

 with a long iron forceps I carefully broke off the sealed end of the bubble under 

 water, so as no bubble of air appeared to emerge or escape through the water, 

 but the liquor by the weight of the atmosphere sprung into the empty part of 

 the glass bubble, and filled the whole cavity about half full ; and presently, as 

 I foretold, the bubble subsided, and made its scale preponderate so much, that 

 there needed 4 drachms and 38 grains to reduce the balance to an equilibrium. 

 Then taking out the bubble with the water in it, by the help of the flame of a 

 candle, warily applied, we drove out the water (which otherwise is not easily 

 excluded at a very narrow stem) into a glass counterpoised before ; and as we 

 expected, we found it to weigh about 4 drachms and 30 grains, besides some 

 little that remained in the egg, and some that may have been rarefied into va- 

 pours, which added to the piece of glass that was broken oft' under water and 

 lost there, might very well amount to 7 or 8 grains. By which it appears, not 

 only that water has some weight in water, but that it weighs very near, or al- 

 together, as much in water as the self-same portion of liquor would weigh in 

 the air. 



The same day we repeated the experiment with another sealed bubble, 

 larger than the former, being as large as a great hen-egg, and having broken 

 this under water, it grew heavier by 7 drachms and 34 grains ; and having 

 taken out the bubble, and driven out the water into a counterpoised glass, we 

 found the transvasated liquor to amount to the same weight, abating 6 or 7 



