Sydney Earth. — E.xpnimnils en BmviI. 411 



and more w^ter threw dou-n a little more. 3. Klaproth's marine folutior. airorcled a pre^ 

 cipitate by the addition of an alkali which was folublein vitriolic acid, and afforded alum. 

 Wedgwood's precipitate by means of water was infoluble in the nitrous or vitriolic acids. 

 The mdirea folution of this matter in vitriolic acid was precipitated by water. 4. M. Klap- 

 roth's experiments Ihewed nothing but filex, alumine, and a minute portion of iron. He 

 thmks It probable that Wedgwood's precipitate by water was (ilex combined with akimine. 

 But m Wedgwood's experiments this matter was fufed without addition in an hole fcooped 

 m charcoal, and alfo in an hole in a lump of chalk, to which it did not adhere. Kirwan * 

 found equal parts of alumine and filex infufible at ibo" of Wedgwood ; and Achard found 

 them infufible in a porcelain furnace, in all proportions ; not to mention that very refraclory 

 veffels are made out of the fame two earths mixed together. 5. I do not fee how Wedg- 

 wood's method of fubfidence and decantation could have left any thing fufpended which 

 Klaproth's filtre could have detained. 



Hence it feems fair to conclude that the two minerals were not the fame, however this 

 may have happened ; and that the exiftence of the new fufible earth of Wedgwood ftands 

 on the fame evidence as before, namely, his expoiments, which have not yet been repeated 

 that I know of. j i > 



V. 



A Philcfophical Manoir, contahnng-i. Experiments relative to the Propagation of Soundin dif- 

 ferent So!.dandFlu:dMeduans.-Jnd 2. An E.perUnental Enquiry into theCaufe of L 

 Refinance of Mufical InJIruments. By M. Perrole\. With Annotations 



Ac . 



nijf^ '"' '/'"J''""'"" °J ^"""'^ ''^'•°"g'^ ^^'f^t. 'trough air of greater or lefs denfity J. 

 and through different gaeousfubftances II, has added to the amount of our philofophical 

 knowledge, I have thought an abundant harveft of new fads might be obtained by caufinj: 

 found to pafs through a great number of bodies of different kinds, as well folid as fluid, and 

 comparing their effe£ls together. 



_ Thefe are the views whicb have direfted the experiments of which I fliall give an account 

 .n the firft part of this memoir j and in the fecond 1 fhall avail myfelf of the refults in an 

 endeavour to afcertain the caufe of the refonance of bodies. 



PART I. 



AS all the trials depend upon the following experiment, it is neceffary to give particular 

 attention to its detail. ' ^ F-'^-'i-uKir 



^>W,„.„, /. and chief Clofe the ears with chewed or mafhed paper ; fufpend a watch by 

 .n hook. Place the ear at the diftance of two lines from the watch, and you will not hear l 



• Mineralogy, i. 58. 



t Mem. (Ic I'Acad. Royale <le Turin, v. 1,5. 



: Nollft, Mcin. dc I'Acad. Roy.ilc dc Paris, 1743. 



§ Miifclitnbrock, n. .441.-N0IICI, Lc(;ons dcPJiyfisiic-, in 3^5 

 ^^U^PrieftleysExrcrimcn,. and Obfcrvaii.nV^-c. and ,.y E.,,.cri,ncms i,. ,!.c Torin Mcmci. for „S6, 



^ vibrations. 



