496 PHILOSOPHICAL TRANSACTIONS. [ANNO 1799. 



ovarium nor a testicle, sometimes bearing a greater resemblance to the one, some- 

 times to the other; and may according to circumstances, either remain in the natural 

 situation proper to the testicle, whether it is the scrotum of the male, or the labia 

 pudendi of the female. 



XT. An Inquiry concerning the JVeight ascribed to Heat. By Benjamin Count of 

 Rumford, F.R.S., M.R.I. A., &c. p. 179- 



The various experiments which have hitherto been made with a view to deter- 

 mine the question so long agitated, relative to the weight which has been supposed 

 to be gained, or to be lost, by bodies on their being heated, are of a nature so 

 very delicate; and are liable to so many errors, not only on account of the imper- 

 fections of the instruments made use of, but also of those, much more difficult to 

 appreciate, arising from the vertical currents in the atmosphere, caused by the hot 

 or the cold body which is placed in the balance, that it is not at all surprizing that 

 opinions have been so much divided, relative to a fact so very difficult to ascertain. 

 It is a considerable time since I first began to meditate on this subject, and I have 

 made many experiments with a view to its investigation; and in these experiments, 

 I have taken all those precautions to avoid errors, which a knowledge of the various 

 sources of them, and an earnest desire to determine a fact which I conceived to be 

 of importance to be known, could inspire; but though all my researches tended to 

 convince me more and more, that a body acquires no additional weight on being 

 heated, or rather, that heat has no effect whatever on the weights of bodies, I have 

 been so sensible of the delicacy of the inquiry, that I was for a long time afraid to 

 form a decided opinion on the subject. 



Being much struck with the experiments recorded in the Transactions of the r. s. 

 vol. 75, made by Dr. Fordyce, on the weight said to be acquired by water on being 

 frozen; and being possessed of an excellent balance, belonging to his most Serene 

 Highness the Elector Palatine Duke of Bavaria; early in the beginning of the 

 winter of the year 1787, — as soon as the cold was sufficiently intense for my pur- 

 pose, I began to repeat those experiments, in order to convince myself whether the 

 very extraordinary fact related might be depended on; and with a view to removing, 

 as far as was in my power, every source of error and deception, I proceeded in the 

 following manner. Having provided a number of glass bottles, of the form and 

 size of what in England is called a Florence flask, blown as thin as possible, and of 

 the same shape and dimensions, I chose out from among them 2, which, after 

 using every method I could imagine of comparing them together, appeared to be 

 so much alike as hardly to be distinguished. 



Into one of these bottles, which I shall call a, I put 4107.86 grains Troy of 

 pure distilled water, which filled it about half full; and into the other b, I put an 

 equal weight of weak spirit of wine; and, sealing both the bottles hermetically, 

 and washing them, and wiping them perfectly clean and dry on the outside, I sus- 

 pended them to the arms of the balance, and placed the balance in a large room, 



