FRAGMENTS OF SCIENCE. 



569 



equipment for that struggle. If we compare 

 as best we may with our limited information 

 the general characteristics of the high-fed 

 and low-fed classes and races, there is, I 

 think, to be perceived a broad distinction 

 between them. In regard to bodily strength 

 and longevity the difference is inconsider- 

 able, but in regard to mental qualities the 

 distinction is marked. The high-fed classes 

 and races display, on the whole, a richer 

 vitality, more momentum and individuality 

 of character, and a greater brain power than 

 their low-fed brethren ; and they constitute 

 the soil or breeding ground out of which 

 eminent men chiefly arise.' It is well under- 

 stood that differences in mental capacity may 

 be explained, in part at least, by differences 

 in the type of nutrition of the brain cells, 

 and nutrition is unquestionably modified and 

 influenced by the quality of the food con- 

 sumed. To again quote Sir William Roberts : 

 ' Trainers will tell you that the hunter and 

 the draught horse require to be fed diifer- 

 ently. In the hunter is wanted rapid libera- 

 tion of energy within a comparatively short 

 space of time ; in the draught horse is wanted 

 a more gradual liberation of energy and for 

 a longer period. The hunter is fed on a con- 

 centrated and stimulating food, the heaviest 

 and most expensive oats, which, if I may so 

 express it, is the beef of the vegetable feeders, 

 while the draught horse is fed on a lower and 

 less stimulating diet — on Indian corn and 

 chopped hay, food which tends to increase 

 bulk and weight.' So with mankind, the 

 nature and quality of the nutrient — aside 

 from its containing the due proportion of the 

 several requisite elements — exert a specific 

 influence upon the character of mind and 

 body ; and meats may be fairly placed in 

 the front rank of foods as giving important 

 aid toward that higher physical and mental 

 development which belongs to the civiliza- 

 tion of the nineteenth century." 



Uranimn. — Until the introduction of the 

 electric furnace by M. H. Moissan, the oxides 

 of many of the metals had been looked upon 

 as irreducible by carbon. M. Moissan, three 

 years ago, isolated the metal uranium in this 

 way. The metal, when pure, is perfectly 

 white, and is not magnetic. It has the re- 

 markable property of emitting invisible phos- 

 phorescent rays capable of producing photo- 



graphic effects through a medium opaque to 

 ordinary light vibrations. The effects are 

 precisely similar to those previously obtained 

 from uranium salts, except that they are 

 nearly four times as intense. The chemical 

 behavior of uranium depends to a certain ex- 

 tent upon its state of division. The metal 

 obtained by electrolysis, which is finely di- 

 vided, takes fire in fluorine, is attacked by 

 chlorine at 180°, by bromine at 210°, and by 

 iodine at 260°, the reaction in all cases being 

 complete. The powdered metal is completely 

 burned in pui-e oxygen at 17o°, and decom- 

 poses water slowly at the ordinary temper- 

 ature, but more quickly at 100°. Uranium 

 is one of the rapidly increasing group of 

 metals which combine directly with nitrogen 

 at high temperatures, and hence in its prepa- 

 ration it is necessary to work in such a 

 manner as to completely exclude the air. 



Working in Compressed Air. — E. W. 



Moir, in a paper read before a recent meet- 

 ing of the Society of Arts, gave some inter- 

 esting data regarding the effects upon the 

 human system of working in compressed air 

 and the various practical means of lessening 

 the danger and overcoming any sudden col- 

 lapses. Mr. Moir had charge of the work on 

 the Hudson River Tunnel for a time, and 

 has had some connection with most of the 

 underground tunneling ventures of the past 

 two decades. He says : " When I first came 

 to New York the men had been dying at the 

 rate of one man per month out of forty-five 

 or fifty men employed, a death-rate of about 

 twenty-five per cent per annum. With a 

 view to improving this state of things, an air 

 compartment like a boiler was made, in which 

 the men could be treated homoeopathically, 

 or reimmersed in compressed air. It was 

 erected near the top of the shaft, and when 

 a man was overcome or paralyzed, as I have 

 seen them often, completely unconscious and 

 unable to use their limbs, they were carried 

 into the compartment, and the air pressure 

 raised to about one half or two thirds of that 

 in which they had been working, with imme- 

 diate improvement. The pressure was then 

 lowered at the very slow rate of one pound 

 per minute, or even less, the time allowed for 

 equalization being from twenty-five to thirty 

 minutes, and, even in severe cases, the men 

 went away quite cured. No man ever suffers 



