Chemistry and Physics. 303 



acetyl, gives vanillic acid. Creosol is therefore parahydroxyl- 

 metamethoxyl-toluene. From phlorol, methyl-phlorol and oxy- 

 phthalic acid were prepared. — Ber. Bed. Chan. Ges., x, 57, Jan. 



1877. G. F. B. 



8. Measurement of High Pressures. — M. L. Caillktet has 

 recently constructed a manometer capable of measuring high 

 pressures, on the slope of a hill near his laboratory at Chatillon- 

 sur-Seine. The apparatus consists of a metallic tube 70 meters 

 long and about 2 mms. interior diameter. One of the extremities 

 of this tube is soldered to a reservoir of iron filled with mercury 

 and placed at the base of the hill. To the free extremity of the 

 tube a large glass tube is attached, which forms the upper end. 

 When the mercury contained in the reservoir is compressed, it is 

 forced up into the metallic tube so as partly to fill the glass tube, 

 which is fixed on a vertical plate. This portion of the apparatus 

 is movable, owing to the flea llio tube and may 

 be carried to one side and placed against either of several stakes 

 arranged along the slope and having indices distant from each 

 other exactly 760 mms. vertically. Fractions of an atmosphere 

 ed by a graduated scale resting against the stake. 



pressure of thirty-four atmospheres may thus be obtained. M. 

 Cailletet proposes shortly to measure the compressibility of gases 

 at very high pressures by the aid of the shaft of a deep mine. 

 For this purpose it is onfv necessary to lower into the shaft to a 



previouslv used 



£ or this purpose it is only necessary 1 

 known depth a cylindrical' re 



in testing the law of Mariotte. A small metal tube starting at 

 the surface is attached to the iron reservoir. When mercury is 

 turned into the extremity of the metallic tube, it descends into the 

 reservoir and produces a pressure which is transmitted to the gas 

 m the interior. This m-essmv is accuratelv measured by the dif- 

 ference of level , be two tubes. Thus with no 

 special apparatus and simply by the aid of mercury we can com- 

 press a gas several hundred atmospheres and at the same time 

 measure exactly the pressure produced.— Comptes B< wdus, Ixxxiv, 



9- Diathermaneity of Metals and Paper.- -M. Avmonnkt. from 

 Jw own observations, together with those of Wiedemann and 

 *ranz, on the rapidity with in of temperature 



is established in bars whose roethYients of conductlbillty are 

 sought, arrives at the following conclusions: _ 



1st. That metals and paper are not athermanoqs as is generally 

 supposed. 



2< i- That they are more diathermanous for the obscure rays 

 emanating fro,,,* , Jit to a temperature below 



1 ," u than for the luminous heat ravs. or those near the red end of 

 the spectrum. 



3d. That they have absorbent •■-■- '— t} ' :1 !' that of water. 

 ^ complement of the inverse ratio which exists between the 



