On the Action of Solids in liberating Gas from Solution. 385 



conclusion that the antennae serve to a considerable extent as 

 organs of touch in the female ; for the palpi are extremely 

 short, while the antennse are very movable and nearly equal 

 the proboscis in length. In the male, however, the length 

 and perfect development of the palpi would lead us to look for 

 the seat of the tactile sense elsewhere ; and in fact we find the 

 two apical antennal joints to be long, movable, and compara- 

 tively free from hairs, and the relative motion of the remaining 

 joints very much more limited." 



My experiments on the mosquito began late in the fall ; and 

 therefore I was not able to extend them to other insects. This 

 spring I purpose to resume the research, and will experiment 

 especially on those Orthoptera and Hemiptera which voluntarily 

 emit distinct and characteristic sounds. 

 [To be continued.] 



LI I. On the Action of Solids and of Friction in liberating Gas 

 from Solution. By Charles Tomlinson, F.R.S.* 



IN the Philosophical Magazine for April 1873, I stated that 

 chemically clean solid bodies, in their behaviour towards 

 gaseous solutions, admit of being arranged into four classes or 

 groups. The first group includes glass and all vitrified and 

 siliceous surfaces, and the denser metals, including mercury. 

 The gaseous solution, whether supersaturated or not, adheres to 

 the chemically clean surfaces of these bodies in the most perfect 

 manner, so that there is no separation of gas. 



The second group includes oils, both fixed and volatile ; fatty 

 bodies whether acid or neutral, various kinds of wax, resin and 

 gum-resin, camphor, spermaceti and similar bodies, not soluble 

 in water. The surfaces of such bodies, though chemically clean, 

 liberate gases from their aqueous solutions ; and they do so the 

 more efficiently, in proportion as their surfaces are less liable to 

 be wetted by the water of the solution. In other words, the gas 

 adheres to such surfaces with greater force than the water. 



When it is said that a body in Class I., not chemically clean, 

 liberates gas from solution, it is contaminated more or less with 

 one of the substances in Class II. 



The third class consists of porous solids which are eminently 

 active in liberating gas from solution. This class includes woods 

 of all kinds, hard and soft, and the charcoals made from them ; 

 also coal, coke, anthracite, jet, plumbago, roll sulphur, pumice, 

 meerschaum, bone, ivory, chalk, lime, indigo, and the less dense 

 metals, such as aluminium and magnesium ; and lamillar metals 



* Communicated by the Author. 

 Phil. Mag. S. 4. Vol. 48. No. 319, Nov. 1874. 2 C 



