176 



PURE HYDROGEN GAS INODOROUS. 



OBSERVATIONS AND EXPERIMENTS UPON 

 MECHANICAL AGENTS. 



Sir n. Davy, in conjunction with Mr. 

 Faraday, lias made a variety of experi- 

 ments with the view of ascertaining 

 whether the vapors arising from the 

 Hquified gases might not be rendered 

 available as mechanical agents, in lieu 

 of steam, and be applicable to the same 

 purposes. These experiments having been 

 detailed in a paper read at the Royal In- 

 stitution, we have made the following 

 selections from it, considering them to be 

 well deserving the attention of our scienti- 

 fic mechanical readers. 



Siilphuniled hi/drogen, which condenses 

 readily at 3° Fahrenheit, under a pres- 

 sure equal to that which balances the 

 elastic force of an atmosphere compres- 

 sed to 1-I4th, had its elastic force in- 

 creased so as to equal that of an atmos- 

 phere compressed to l-17th, by an in- 

 crease of 47° of temperature. 



Liquid nuiriatic acid at S° exerted an 

 elastic force equivalent to that of an at- 

 mosphere compressed to l-20th; by an 

 increase of 22°, it gained an elastic force 

 equivalent to that of an atmosphere com- 

 pressed to l-25th; and by a further ad- 

 dition of 26° an elastic force equivalent to 

 thatof air condensed to l-40lh of its primi- 

 tive volume. Sir H. Davy considers that 

 the denser the vapor, or the more difficult 

 the gas is of condensation, the greater 

 will be its power under changes of tem- 

 perature as a mechanical agent — Thus : 



Carbonic acid exerted a force nearly 

 equal to that of air compressed to l-20th 

 at 12° Fahrenheit; and of air compres- 

 sed to l-3Gth at 32°, making an increase 

 equal to the weight of 13 atmospheres by 

 an increase of 20° of temperature; and 

 this immense elastic force of 36 atmos- 

 pheres being exerted at the freezing point 

 of water. 



From the above experiments, as well 



as others -on the same subject, Sir H. 

 Davy is of opinion that "the small dif- 

 ferences of temperature required to pro- ^ 

 duce an elastic force equal to the pressure 

 of many atmospheres will render the risk 

 of explosion extremely small; and (he 

 continues) if future experiments should 

 realize the views here developed the mere ' 

 diderence of temperature between sun- 

 shine and shade, and air and water, or 

 the effects of evaporation from a moist 

 surface, will be sufficient to produce re- 

 sults which have hitherto been obtained 

 only by a great expenditure of fuel. 



Sir H. Davy has employed a very sim- 

 ple method of liquifying the gases by the 

 application of heat. The gas is placed 

 in one leg of a bent sealed tube con- 

 fined by mercury, and applying heat to 

 ether, alcohol or water, in the other end. 

 In this manner prussic gas, and sul- 

 phurous acid gas were liquified by the 

 pressure of the vapor of ether. 



The reproduction of these gases oc- 

 casioned cold. — ib. 



GAS FROM PYROLIGNEOUS ACID. 



When wood acid is made to pass 

 through an iron tube heated to bright 

 ignition, and the acid allowed to enter 

 the tube by drops in quick succession, gas 

 of a very excellent quality is obtained. 



ib. 



PURE HYDROGEN GAS INODOROUS. 



A perfectly inodorous hydrogen gas 

 may be obtained by putting an amalgam of 

 potassium and mercury into distilled 

 water ; and by the addition of an acid, 

 or the muriate of ammonia to the water, 

 the same odor is produced as in the solu- 

 tion of zinc by diluted sulphuric acid; 

 this shows that pure hydrogen is inodor- 

 ous, and that the odor which usually ac- 

 companies the gas is owing to impurities. 



ib. 



CONTENTS OF NO. 11. VOL. X. OF OBSERVER AND RECORD. 



M. Cozzi's Method of obtaining Creosote, . . 161 

 A valuable Green Color extracted' from Coffee 



Berries, 161 



Sir H. Davy's Agricultural Chemistry, . . . 162 



Definition of Terms. Letter I, 164 



Process of making the Schweinfurt Green Dye, 175 



A cheap and valuable Filtering Machine, . . 175 



Valuable Flux for the Blow Pipe, .... 175 

 Observations and Experiments upon Mechanical 



Agents, . . , 176 



Gas from Pyroligneous Acid, 176 



Pure Hydrogen Gas Inodorous, 176 



