On the Identity of the Pyro muceuf, Pyro-tartareouSt and PyrO'ttgneous Jcids, lie, 9* 



XII. Of the Frequency of Vibrations conjlituting a given Note, 



7'I)C number of vibrations performed by a given found in a fecond, has been varloufly 

 afcertained ; firlt, by Sauveur, by a very ingenious inference from the beats of two 

 founds ; and fince, by the fame obferver and feveral others, by calculation from tlic 

 weight and tenfion of a chord. It was thought worth while, as a confirmation, to make 

 an experiment fuggefted, but coarfely condufted, by Mcrfennus, on a chord 200 inches in 

 length, (Iretched fo loofely as to have its fingle vibrations vifible ; and, by holding a quill 

 nearly in contaft with the chord, they were made audible, and were found, in one ex- 

 periment, to recur 8.3 times in a fecond. By lightly prefling the chord at one-eighth of 

 its length from the end, and at other fliorter aliquot diftances, the fundamental note was 

 found to be one-fixth of a tone higher than the refpeftive oftave of a tuning-fork marked 

 C : hence, the fork was a comma and a half above the pitch affumed by Sauvcur, of an 

 imaginary C, confifting of one vibration in a fecond. 



(To be concluded in our next.) 



II. 



Oft the Identity of the Pyro-mucous, Pyro-tartareous, and Pyro-ligneous Acids., -with the Acetous 

 Acid. By Citizens FouRCROY and Vauqjjelis*. 



T 



■M- HE re-union of fpecies which have been erroneoufly confidered as diiFerent, is in many 

 inftances of greater advantage to the fcience of fads, than the difcovery of new fpecies. 

 It is towards this degree of perfedion that the efforts of chemifts and naturalifts are at 

 prefent directed. 



Three acids have been diftinguifhed by different appellations, in which the common pro- 

 perty of being produced by the aftion of fire, and of acquiring feveral common charadlers 

 from that agent, is well known ; but it was never imagined that they are not only identi- 

 cally the fame, but likewifc analogous in their nature to the acid of vinegar, denominated 

 acetous acid. Citizens Fourcroy and Vauquelin, in their endeavours to difcover certain 

 charaflers by which the pyro-mucous, pyro-tartareous, and pyro-ligneous acids might be 

 diftinguifhed, were unable to difcover any. By comparing thofc which have hitherto 

 been pointed^ out as the di(lin£live charaflers, it may be (hewn, as they have done, 

 that they are founded merely on flight differences of fmell and colour 5 and are con- 

 fequently delufive. 



• Bulletin de la Soe. Philom. — N. 



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