Sensibility of the Human Ear for the Pitch of Musical Notes. 523 



were mixed, the mass assumed a crumbly appearance : there 

 was no action in the cold ; but when heated to 60° a copious 

 disengagement of hydrochloric acid gas took place, and a yel- 

 lowish liquid was formed which commenced to boil at 83°. 

 When this liquid was treated with water, a white flaky substance 

 was deposited which crystallized from alcohol in beautiful feathery 

 interwoven crystals. These, on analysis, were found to have the 

 formula C 20 H 15 C1, and their formation was obviously in accord- 

 ance with the equation 



C 20 H 16 2 + PC1 5 =P0 2 C1 3 + HC1 + C 20 H 15 C1. 



When two equivalents of pentachloride were used for one of 

 camphor, the reaction was found to be essentially the same, but 

 the mass required to be heated to 100°. On subsequent mix- 

 ture with water a viscous oil separated, which only became solid 

 after a few days. This mass, by suitable treatment, yielded the 

 body C 20 H 16 ' CI 2 in crystals like the first. Placed over sulphuric 

 acid, it gave off hydrochloric acid, and produced the first com- 

 pound. It is probable that its formation proceeds in accordance 

 with the equation 



C 20 H 16 O 2 + PCl 5 =PO 2 Cl 3 + C 20 H 16 Cl 2 , 



and that, in consequence of the heat, a portion of the body 

 C 20 H 16 CI 2 is decomposed. 



This latter chloride was treated with sodium-alcohol, acetate 

 of silver, and with ammonia, but the experiments did not give 

 definite results. The compound C 20 H 15 CI does not act on the 

 plane of polarization. The other produces a small right devia- 

 tion. 



LXXI. On the Sensitiveness of the Human Ear to the Pitch of 

 Musical Notes. By F. Fessel*. 



THE Conservatory of Music at Cologne has recently decided 

 on adopting, as a standard, the new Parisian tuning-fork ; 

 and the Concert Society here intend introducing the new pitch 

 at the next winter concert. 



In consequence of my having expressed a wish to possess a 

 tuning-fork precisely similar to that belonging to the Conserva- 

 tory, the fork that had been procured from Paris was kindly 

 placed at my disposal. 



In tuning forks I invariably pursue Scheibler's plan, which 

 has hitherto proved itself the only safe one. The fork to be 

 tuned, before having its vibrations compared with the seconds' 

 pendulum, is, as is well known, tuned as far as possible by ear. 

 My instrument and the seconds' pendulum happening on this 



* Translated from Poggendorff's Annalen, No. 9, 1860, by F, Guthrie, 



3M3 



