756 FOREIGN C0BBB8P0NBENGE. 



raaladies. "Pen the disease, make a void round it, capture it by famine." 

 The most effectual method for counteracting croup, whether in hospitals or 

 families, is isolation. In the case of diphtheria, this plan is adopted in 

 French hospitals, and with great success. 



Matter presents itself under three forms: solid, liquid and gaseous. A 

 gas operated upon, under certain conditions, will become a liquid, and the 

 liquid solid. Ice can be changed into water, water into vapor. This rule 

 ought to be general ; they are the energetic means alone which are wanting. 

 Faraday liquefied several permanent gases by means of a freezing mixture 

 composed of solid carbonic acid ; but several gases, such as oxygen, hydro- 

 gen, nitrogen, oxide of carbon and bi-oxide of nitrogen resisted all his 

 experiments. M. Cailletet, a distinguished chemist, has succeeded in lique- 

 fying bi-oxide of nitrogen by a new process. In a gas, the constituent 

 atoms are wide aj)art ; in a liquid, not so much; and least of all, in a solid. 

 To liquefy a gas the atoms must be brought Learer to each other, then com- 

 pressed, and next congealed. Cold is the most energetic of these reducing 

 agents. After compressing a gas by means of a hydraulic pump, JVE. Caille- 

 tet liquefied it afterwards with the ordinary freezing mixtures. When the 

 pressure is suddenly removed, the gas expands, and as is well known, the act 

 of expansion produces a diminished temperature. The experimenter has 

 demonstrated, what others have suspected, that there is a "critical point" of 

 temperature, above which no gas can be liquefied. The practical applica- 

 tions of the beautiful discovery made b}'' M. Cailletet can be immense. He 

 has liquefied carburet of hydrogen, consisting of two elements, carbon and 

 hydrogen. Now if he could obtain the carbon in a crystallized form, that 

 would be the diamond. 



M. de Chancourtois, an eminent engineer, latel_y asked if the diamond 

 was not produced by a reaction, similar to that which engenders sulphur in 

 certain localities where sulphuretted hydrogen, escaping from the fissures, 

 the hj^drogen unites with the oxygen of the air and forms water, the sulphur 

 being deposited in the state of crystal. Eeplace the sulphurous by emana- 

 tions of carbon, and the latter may be also deposited in a crystallized fbrra_ 

 Where diamonds are most found, is exactly in that geological period — the 

 Devonian, remarkable for bituminous impregnations, thus marking the in- 

 tensity of carbon emanations. This negative solution in favor of the man- 

 ufacture of diamonds is valuable. 



So great is the inattention to the proper fitting up of school-rooms, that 

 the wonder is, so many persons escape being hunchbacked or shortsighted. 

 The seats and desks are generally of a uniform pattern for large as for 

 small boys, deforming thus the vertebral column, and the lighting is so de- 

 fective that 22 per cent, of the pupils, of French primary schools especially, 

 are shortsighted, and this affliction becomes more pronounced the longer 

 lads remain at school, that is to say, pass to the secondary schools or colleges. 



