200 Miscellaneous Intelligence. 



made to surpass Dn Goring^s improved Amician Engiscope; and it 

 seems equally certain that no other reflector will ever be invented 

 capable of the same facilities of application to the examination of 

 both opaque and transparent objects. If Professor Amici has been 

 beaten, it has been done with his own weapons, — the copy has sur- 

 passed the original, — the child, by virtue of foreign nursing and 

 tuition, has exceeded the stature and strength of the father. 



1. On the Specific Heat of Gases, by MM. de la Riv^ 4ind Mar- 

 cet. — The principle on which these philosophers proceeded in their 

 researches, was, to expose equal volumes of different gases to an 

 equal source of heat during equal times, and to judge, by the aug* 

 mentation of elastic force in each gas, the temperature which it had 

 acquired. The apparatus was a kind of manometer, and consisted 

 of a glass balloon to retain the gas, and a bent tube attached to it, 

 which, descending into a vessel of mercury, served to show, by the 

 column of metal within it, what was the elasticity of the gas. 

 This method was adopted, because, i. The gas was not altered in 

 volume by the change of temperature, its elasticity only changing ; 

 ii. The temperature was indicated by the gas itself, and not by a 

 thermometer : iii. Water was easily separated previously from the 

 gases, and excluded from the apparatus : iv. All the gases were 

 placed in exactly the same circumstances, so as to render it unne- 

 cessary to refer to any calculation for the purpose of comparison. 



Two methods of applying heat were resorted to : in one the bal- 

 loon, containing the gas at a certain temperature, was placed in 

 water at a higher but constant degree, for a certain time (generally 

 4''), and the elevation of temperature noticed : in the other, the bal- 

 loon with the gas was inclosed in a larger copper balloon, blacken- 

 ed inside, and the space between the two exhausted as much as 

 possible of air ; the apparatus being then immersed in warm water, 

 the heat gained access slowly to the gas, and the time] of each 

 experiment was increased, at the same time that certain sources 

 of error were avoided. 



The gases experimented with were, atmospheric air, oxygen, 

 azote, hydrogen, carbonic acid, olefiant gas, oxide of carbon, ni- 

 trous oxide, nitrous gas, sulphuretted hydrogen, ammonia, sul- 

 phurous acid, muriatic acid, and cyanogen. Great care was taken 

 in their preparation. The result of the experiment was very unex- 

 pected ; for, during the five minutes allotted for each, all had ac- 

 quired the same temperature, — a circumstance which proves that 

 they all have the sa7ne specific heat The equal volumes of gas at 

 the pressure of 65 centimeters (15.59 inches) and the temperature 

 of 20° C, being exposed to a source of heat at 30° C, acquired a 

 mean temperature of 6.32 degrees in five minutes, the extreme dif- 

 ference, in any of the experiments, not being more than 0.04 of a 



