ijS Alalhinkiiiail Correpwdciicc- 



fpccific gravity of the folution given being 1.1213, wc fluU find, from the table in p. 39, 

 that it contained about C.1581 of fait, or 44+ grains in the whole; being near 29 grains lefs 

 L'un what would refuU from mere computation. 



*,* The above was the ;nif A-cr fent previous to the appearance of the Editor's note, p. 191. 

 )•. was fudiciently aw.ire that the abovementioncd table was not to bo relied on to indicate 

 the fpceilic gravities of all uoinb'e foluiions of common fait in water -, which indeed he con- 

 ceived to be \o obvious as to preclude the neccflity of more reftriftivc terms. It is however 

 certainly true, that, if Baumc's eonflrudlion of tiie inRrument, and De Morveau's obfeiva- 

 tion, were both coireil, the tabular fpecific gravity anfwering to 15° would be accurately 

 that of the folution of 0.15 of fait ufed by the former; and that the errors of tlie tabic, 

 for all inferior degrees of fa'.uration, would be thofe only arifing from the hypothcfis of 

 equal graduation on wliich it is calculated ; which, as the Editor obferves, p. 192, are pro- 

 'lably not very conliderablc. According, therefore, to this mode of reafoning, the table 

 ought to be perfefHy correft about that degree, and ferve well enough for giving nearly 

 the fpecific gravities of all aqueous folutions of common fait, in which its propor- 

 tion does not exceed 0.17. or 0.18. The great difFerence between this table and that of 

 Dr. Watfon (p. 192), which gives upwards of c.i8 of fait, inllead of 0.15, for the fpecific 

 gravity of 1.1141 feems only to be attributable to the reafons alTigned p. 38. Perhaps 

 M. Baume had either expofed the fait to a confiderable heat before he dilTolved it, or fuffered 

 the folution to evaporate before he ufed it for the inflrument which fell into the hands of 

 M. De Morveau ; or poffibly even its fcale had been transferred from another whofe Hem 

 bore a fmaller proportion to its bulb. The latter table is probably the raofl; to be depended 

 on in all cafes. 



NEW MATHEIilATICJL QUESTION. 

 QtTEsrioN IX. B^' Tkiconometricus. 

 THE angles of elevation of a terreflrial objedt fituated above the horizon, taken at 

 three given flations in a horizontal plane, being giveii ; it is required to determine from 

 thence its perpendicular height. 



NEIV PUBLICATIONS. 



Count Rumford's Experimental Eflays, Political, Economical, and Philofophical. EfTay VII. 

 Of the Manner in which Heat is propagated in Fluids. Of a remarkable Law which has 

 been found to ob'tain in the Condenfation of Water with Cold, when it is near the Tem- 

 perature at which It freezes ; and of the wonderful Effects which are produced by the 

 Oper.ition of that Law Sn the Economy of Nature. Together with Conjcfturcsrefpeding 

 the final Caufc of the Saltncfs of the Sea. OQavo, 108 pages, with two plates. Price 2s. 

 ditched. Cadell and Davies, 1797. 



JL HIS elTay, which contains important difcoverles and applications of the dodrlne of heat, 

 will demand particular and more ample notice in the prefent work than can be here given. 

 The author had before proved that the communication of heat through air is aimed totally 



cffeflcd 



