21(3 DESCRIPTION OF A SECRET LOCK* 



liidrogen gas, (Annales de Chimie, torn, I. page 284.) " The 

 " four produces of the dilatation were in this cafe received in 

 " a veflcl which was furrounded wilh another veflel filled with 

 u ice. Notwithstanding this, the mercury of the trough in- 

 f* dicated by the thermometer 2, 3, 4, 6, degrees above zero, 

 " whilft the water of the bath was at the fame time at 20, 40, 

 " 60 arid 80 degrees, which may have occafioned fome inac- 

 " curacy in the valuation of each of thefe products ; but this 

 *' cannot be of great confequence, the dilatation being very 

 " little in thefe firft degrees." 



Hence it may be inferred that thefe philofophers did not pay 

 more attention to reduce the volumes of the other gafes to 

 zero ; and if that was the cafe, this would be another caufe of 

 uncertainty in their experiments. 



J3y comparing the volumes of gafes remaining in the retort 

 with thofe expelled by heat, Cit. Guyton and Duvernois found 

 that oxigen, hidrogenous and carbonic acid gafes and atmof- 

 pheric air underwent a diminution, and they attributed the 

 caufe of it to the combinations which had taken place during 

 the time of performing the experiments. Yet when I ufed 

 very pure mercury, deprived of oxide, I could not obferve 

 any fenfible action between this metal and the gafes from the 

 temperature of melting ice to that of boiling water. 



( To be concluded in our next.) 



■V- ' ' ' i I ■'"■ I I 



XIV. 



Defcription of a new Secret Lock. By J. B. Berard. 



'Preliminary Reflections. 



Great utility of SOME machines are fo eminentlyufeful as to require no dif- 

 locks. cuflion in that refpecl. They are highly interefting to the 



whole of fociety. Locks are of this number. They are a de- 

 fence fupplementary to the laws, and a remedy for the confe- 

 quences of immorally. From the loweft to the higheft ranks 

 in the itate, there is no one who does not derive daily advan- 

 Secrct locks j 'tage from this invention. And accordingly different ariifts 



* From his Melanges Phyfico Matbematiques. Paris, an 9. 



have 



