SCIENTIFIC.

Otago Witness, Issue 1823, 29 October 1886, Page 35

SCIENTIFIC.

—The meteors > coming tb our earth without, excepting as to their- superficial vitrification, undergoing. any,,chang|i:|7e are able by subjecting them to 'Jmalys'fcito derive from them some precise' , facts/^specting > the constitution of tne' bodies' jji space. , The first fact, which, comes"! out from' hundreds of analyses, is that ,they! have-" not brought a single substance' .which •• is ,'fof^ign to, our globe. About 22 ingredients knpwn to the chemistry of the .eqrifh have fce'enrecognised as present in them. f A,mong .these iron, magnesium, nickel, sulphur, phosphorus, and oarbon are the mos.t, important.. yVhile they are all clad externally in. a cpitni^bn livery, meteorites, when examined in tftejjr fractured parts, along "with traits' of similaVjty, present considerable differences. ' They..'sa.ve been classified, according to their typj&Jinto four groups, according tp.thepropor^o^of iron, they contained. . Those 1 the ! |Ajk group are composed almost wh.qlj.y pf ;^n, which is known as meteoric ■. ir,onl -It & always alloyed with nicJseb&nd'afW'othqr^metals, and contains carbon' free or, in combination, as in steel, .with, frequently". sulphlu^et and phosphuret of iron, it\ scattered globes and grains. It is. always -recpgnjssbto; by a single peculiarity in Mts^tructurp.'^lf we moisten 'a polished surface I 'of* it^'with an acid, we shall immediately observe 'the ap* pearance of numerous straight line;?, as line and as true in their parallelism as/af made with an" engraver's* tool; aria croaaijig on« another in a network <5f regular geometrical figures. These design*;, oalle4 tho ftfiyces of

Widm'anstaetteh, after the first observer of hem, result from, the fact that the metal is not of homogeneous constitution. It is composed of two alloys of iron and nickel, in a crystalline condition, one of which, not being affected by the acid, stands out in relief from the other, which is attacked by it. The meteorites of this group are called • holosiderites," ■or all "iron, in distinction from the others, which contain also stony matters. They are vastly more rare than those of the other groups. The stony substances of the other groups consist chiefly of silica in combination with magnesia and fieroxide of iron-, as peridote or pyroxene, f these silicates are in small proportion and thinly scattered through the iron, they are " syssiderites" ; if' 1 it is the iron that is in relatively small proportion and appearing only in isolated "grains, they are " sporadoiderites." In other meteorites, comparatively few in number, no metallic iron can be perceived, an&they are oalled "asiderites." The most interesting specimens among them are remarked by 'their dull-black colour and a general appearance like that of peat or lignite. Besides stony matters, they contain carbon in combination with hydrogen and oxygen, a chemical quality which has led to their being examined for remains of organic beings, but no trace of anything of the kind has been discovered.— Popular Science Monthly for July. —Sometimes slowly-healing wounds, with feeble granulations, are made to increase their actviity in the direction of cicatrization by transplanting minute fragments of epidermal tissue containing some of the cells of the rete Malpiffhii x>n the healing, surface. O. Petersen has successfully used the sMn from the back of a frog. The slowly-cicatriz-ing wound was situated at the back of the neck of a man, aitjd had resulted from excision of a malignant pustule. A piece of frog's akin the size of the thumb-nail was washed in a 2 per cent solution .and placed upon blotting-paper, when it was divided into two. The grafts were applied' to*the wound so that the blotting-paper was interposed between them and the fixihg-plaster. Two days after the transplantation- both fragments of epidermis were found to be adherent. Two days later a fresh grafting was made : the former grafts had become roseate. In a further period of forty-eight hours the pigmentation of the grafts had almost disappeared. The cicatrix resulting after this treatment was found to be of great softness and elasticity, tfrog's skin as grafts has been recently employed at some of the London Hospitals.— London Lancet. 1 ' . ■