Intelligence and Miscellaneous Articles. 



371 



with great care by R. Schulze. For each single measurement from 

 about a half to three quarters of an hour was required. 



I. Grlass Powder. 



p 



n 



P 



7T 



Temp. 



s 



9-2554 



19-4095 



14-3788 



22-4468 



o 



15-7 



2-4559 



9-2554 



19-4095 



10-5368 



20-1689 



16-4 



2-4547 



9-2554 



19-4095 



13-608 



21-9894 



15-1 



2-4553 



9-2554 



19-4095 



13-271 



21-7895 



16-4 



2-4551 



II. Sulphate of Barium. 



p 



n 



P 



TT 



Temp. 



s 



9-2554 



19-4095 



10-5962 



20-445 



14°-9 



4-3958 



9-2554 



19-4095 



11-7652 



21-3484 



14-9 



4-3962 



9-2554 



19-4095 



14-333 



23-3323 



14-5 



4-3969 



9-2554 



19-4095 



13-0445 



22-3368 



14-5 



4-3967 



The specific gravities differ from one another by not quite a 

 unit in the third decimal place, a result which may be regarded 

 as extremely satisfactory. 



If a greater number of determinations of specific gravity have to 

 be effected, it would be advisable to employ several pycnometers, 

 attached to different arms connected with the air-pump and ex- 

 hausted simultaneously. This would effect a pretty considerable 

 saving of time. — Wiedemann's Annalen, 1882, xvii. pp. 983-985. 



ON THE UPPER LIMIT OF THE PERCEPTIBILITY OF SOUNDS. 

 BY E. PAUCHON. 



I have the honour of communicating to the Academy the results 

 of some researches on the determination of the upper limit of per- 

 ceptibility of sounds, a portion of which were made in conjunction 

 with M. L. Bertrand. 



I proposed to ascertain if, as several physicists have alleged 

 (although they have not brought forward any experiment proving 

 their assertion), this limit varies, for one and the same ear, with 

 the intensity of the sound. For this purpose I employ a powerful 

 Caignard-Latour siren, modified in some of its parts, and set in 

 action by a jet of steam. Various arrangements, described in a 



