POPULAR MISCELLANY. 



427 



fields of bananas and pineapples dotted with 

 orange and mango orchards, which stretch 

 for miles beside the sugar plantations, are 

 nearly all Chinese. They ship fruit to the 

 southern colonies, but their profits must be 

 very small, for one of the principal complaints 

 made against them is that they can make a 

 living where a white man would starve. 

 Nevertheless, it is found that when they 

 hire themselves out to work they are not a 

 very great deal cheaper than white men. 



Worlds and Molecules. In his lectures 

 at Geneva and Lausanne, M. Raoul Pictet 

 presented mechanics as an exact science, 

 comprising chemistry and physics in its do- 

 main. The principal phenomenon of physics 

 is astronomy. The laws of sidereal gravita- 

 tion apply likewise to the smallest bodies on 

 the earth, to infinitely small ones like the 

 molecules, and also to the atoms. Thus we 

 have a unity of matter in which atoms, 

 uniting from molecules, these group them- 

 selves into bodies, and these form worlds. 

 The attraction which controls infinitely large 

 bodies may therefore be regarded as similar 

 to that which unites infinitely little ones. If 

 the atoms touched in a molecule, there would 

 be no force capable of separating them. 

 We are, however, acquainted with dilatation 

 and various ways of separating the atoms 

 and augmenting the distance between them. 

 The hypothesis that they touch is, therefore, 

 not admissible. To explain the theory of 

 chemical phenomena, let us suppose a mole- 

 cule, A, placed somewhere in sidereal space, 

 having a rectilineal motion toward another 

 molecule, B, immovable, and very remote. 

 In its approach to B there will come a mo- 

 ment when A's motion will slacken. Then 

 astronomical phenomena will end and the 

 phenomena special to physics will begin. At 

 last the molecule A will stop ; it has become 

 inert, and can not advance further toward B. 

 It is bound by cohesion. If, now, we sup- 

 pose a pressure to be imposed on A, to bring 

 it down to B, physical phenomena will cease, 

 the resistance of A will diminish with the 

 distance, and finally the molecule will ally 

 itself with B without touching it ; then we 

 have chemical phenomena. The force that 

 unites A and B is affinity. M. Pictet supposes 

 that the absolute zero of temperature, when 

 bodies can no longer react upon one an- 



other, is found between t'^ese last two 

 phases, and his idea is confirmed by experi- 

 ment. When sulphuric acid with potash is 

 cooled down to 150 C. ( 236 Fahr.), no 

 reaction is apparent. The bodies are no 

 longer able to combine at that temperature, 

 when occurs a complete death of such ac- 

 tion. At 80 C. (112 Fahr.), potas- 

 sium remains unattacked in alcohol and 

 water for whole days. A slight warming 

 produces a small reaction ; and if the tem- 

 perature is raised a little more, combination 

 takes place with energy and an explosion is 

 produced. 



Heating and Ventilation of Electric- 

 lighted Bnildings. In his paper on the 

 Heating of Large Buildings, A. R. Wolff, 

 consulting engineer, shows that the intro- 

 duction of electric lighting with isolated gen- 

 erating plants in large buildings has had a 

 sensible effect on the solution of the heat- 

 ing and ventilating problem by practically 

 conditioning the use of exhaust steam for 

 heating. The quantity of steam required 

 for heating such buildings is nearly equal to 

 the amount used independently for their 

 electric lighting. Since electric-light engines 

 convert only about ten or fifteen per cent of 

 the heat of the steam with which they are 

 supplied into mechanical energy, from eighty- 

 five to ninety per cent of it is retained in 

 the exhaust steam, available and just suffi- 

 cient, as a rule, to meet the heating and ven- 

 tilating needs of the building. This means 

 practically that a boiler capacity ample for 

 the heating and ventilating will take care, in 

 addition, of the electric lighting of a large 

 building, or vice versa ; and that in the 

 winter months the electric lighting is se- 

 cured at only a slightly increased fuel expense. 

 It is this fact that makes it difficult for either 

 city or district heating or electric-lighting 

 companies to supply steam or electricity re- 

 spectively to large buildings. They can not 

 compete with the cheapness of generation of 

 the isolated plant within the building. The 

 facts that electric lights give out less heat 

 and vitiate the atmosphere less than gas, and 

 that they do not flicker, have also an impor- 

 tant bearing on the problem of heating and 

 ventilation. The fresh-air supply can be 

 brought in at the top of the room, where 

 there are no lights for it to blow out, and ex- 



