SCIENTIFIC.

Otago Witness, Issue 1932, 30 November 1888, Page 35

SCIENTIFIC.

— The theory is held by Professor Mendeleef, of Russia, that petroleum is produced by water, which penetrates the earth's ernst and oomes in contact with glowing carbides of metals, especially of iron. The water is de* composed into its . constituent ' gases, the oxygen with the iron, while the hydrogen takes up. the carbon and ascends to a higher region, where part of it is condensed into mineral oil and part remains as natural gas to escape wherever and whenever it can find an outlet. If this assumption is correct, and a sufficient store of metalUo carbides is contained in the earth's interior, .petroleum may continue to be formed almost indefinitely and yield a supply of fuel long after the coal has become exhausted. Professor Mendeleef supports his views by producing artificial ..petroleum in a mariner similar to that by which- he believes the natural product is ! made.' „•'.- ' —A very interesting investigation has jnst been made under the direction of the French .Ministry of Agriculture. The results Uemonstrate that sugar is an excellent agent for preserving meat, and possesses some advantages over salt. It is pointed oat the t the latter absorbs a portion of the nutritive substances and of the flavour of meat. When an analysis is made of a. solution- of the salt dissolved by water contained in meat, albuminoid bodies, extractive substances, potassa, and phosphoric aoid are found. Salt deprives meat of those substances so much the more readily in proportion as •it enters the tissues more deeply or acts for a longer time. The result is that the meat when taken from the saline solution has lost nutritive elements of genuine importance. Powered, sugar, on the contrary, being less soluble produces less liquid. It forms around the meat a solid crust, which removes very little water from it and does not alter its taste. Thus preserved, it is sufficient that the meat is immersed in water before using it. -The. report declares that although this treatment costs a little more than preservation by salt/ account must be taken of the final result and of the loss prevented, which off-sets the difference in cost between the two preservatives. ,

—A careful estimate by a Broadway chemist of the contents or constituents of a ton of coal some interesting f acts, not familiar, certainly, to unscientific minds. It is found that, besides gas, a-ton of'ordinary gas coal will yield 15001b of coke, 20gal of ammonia water, and 1401b of /coal tar. Now, destructive distillation of this amount of coal tar gives about 701b of pitch, 171b of creosote, 141b •of heavy oils, about 9Jlb of naphtha yellow, six and one-third pounds of naphthaline, four and three-fourths pounds of naphthol, two and a fourth pounds of alizarine, two and a fourth pounds of solvent j naphtha, one and a fifth pounds of aniline, seventy-nine hundredths of a pound pf-.tolu-dine, forty-six hundredths of a pound of anthracine", and nine-tenths of a pound of I toluches — from the last-named substance being obtained the new product,, sacoharine, said to be 230 times as sweet as the best cane sugar. — Most of the. recent experiments onfbe relative digestibility of different sorss.o£ food have had only a slight bearing on the question of the best diet, for -man,, as they have been either by means of digesting fluids outside of the .animal body or on the lower aninals, and in neither case would a sensible man accept* the results as giving | him much of a clue as to what would be the most wholesome fo,odjhe could take. A GerI man physiologist has reverted to the original j plan of studying digestibility of foods in the actual human subject. He gets volunteer subjects from amongst the students^and pn.ts them on definite diets for a definite* tiipe/fln this way. he has found that- ordinary . fish |is . about as nourishing as lean meat. The result is of some importance in European countries, where the poor cannot get enough meat, but can often obtain cheap fish, They usually consider it as a hardship that they have >to put up with fish instead ,of the meat, which they regard as so much more strengtheh—lf the whole earth were reduced to a uniform level, what would be its. height i above the sea? This a question which was investigated by Humboldt. He found the mean height to depend not so much; on the mountain chains as £o the gentle but compact swelling of the plains, and the development of the tablelands. Thus, he calculated that the distribution of the Pyrenees would proj duce upon the whole of Europe scarcely the ! effect of 6ft, and that of the Alps about 22ft, while the Plateau of Spain, of. far inferior elevation, but more compacti would produce an effect of 76ft. If the vast ranges of the Andes were pulverised, and spread equally over the eastern plain of South America, its effect would be to raise the sur- ; face about 518 ft. The final result obtained I was a mean height above the sea level for | Europe*, of 670 ft; North America, 750 ft; South America, 1130 f t; and Asia, 1160 ft, or a mean elevation for the whole of 920 ft. Africa and Australia are omitted in the preceding calculation, their interiors being then comparatively unknown ; but the now ascertained height of Central Africa, and the general lowness of Australia, would go far to counterbalance one anothdi. " — A botanist,thus describes how the leaves change their colour 1 in ; autumn. i He' ridicules the belief thai frost has anything to | do with it: — '^.The green... matter in the tissue of a leaf is composed of two coloursrred and blue. When 1 the sap ceases to .flow in the autumn/ and. the growth of the tree ceases, oxidation.^f. the tissue takes place. Under certain : conditions the green of the. leaf changes to red; under- different conditions it takes on a yellow or brown tint. This difference in colonr is due to the difference in combination of the original constituents of the green tissue and to . the varying conditions of climate, exposure, and soil. .A dry, cold climate produces more brilliant foliage than one that-is damp and warm. This is the reason that North American autumns are so muchmore gorgeous than those of England." .

— Mrs Parks : " Good gracious,, Henry I What am I to do 1 I can't go to the concert to-night. Somebody has stolen my bustle?" Mr Parks (indistinctly, with bis month full of lather) : " Take the bird-cage." «

(Continued on pagt t7.) .