5o8 



KNOWLEDGE & SCIENTIFIC NEWS. 



[ Al'GUST, 1506. 



of 15 ins. extension fitted with a single Wray lens and a 

 Thorp replica tjrating' ; it shows llie chromospheric spectrum 

 in excellent focus from l{:i to the extreme uUra-vioU-t. 



Objective Prism Comparison Spectrograph 



Various sufjgestions liave been made in recent years for 

 the utihsation of the larj^e light grasping power of objective 

 prism spectrographs in radial motion determinations, the 

 chief difficulty being in the production of a suitable compari- 

 son spectrum owing to the absence of a slit. Mr. De Lisle 

 .Stewart proposes to employ two prismatic cameras mounted 

 together, with their axes inclined, say, about 150 to each 

 other. These will give two spectra close together on the 

 photographic plate, but in reverse order. Two smaller 

 lenses of equal or greater focal length than the main ob- 

 jectives would be placed in the central line of the apparatus, 

 one to serve as guiding telescope and the other to photo- 

 graph a reference image or trail of the star on the plate. 

 By placing the tw-o prisms in these positions it is hoped to 

 avoiil m;my of the flexure difficulties hitherto encountered 

 in this work. 



CHEMICAL. 



Ry C. AiNswoRTH MiTCHELi,, B.A. (Oxon.), F.I.C. 



Air that Extinguished Flame. 



It was recently noticed in a ciikl storage that candles or 

 lamps began to burn with a feeble flame as soon as they 

 were brought into the room, and that in many parts of it 

 they were extinguished. .'\ match could be lit, but the 

 w-ax would not ignite. In the corner of the storeroom was 

 a disused well, from which gas issued, and Mr. Bertram 

 Blount, who w-as asked to investigate the cause of the 

 trouble, at first supposed that carbon dioxide was being 

 distributed into the air from this well. But this was not 

 borne out by analyses of the air in the room and from the 

 well, for the amount of carbon dioxide was only .slightly 

 more than is present in normal air, and was quite insutTi- 

 cient to have affected the combustion of a candle. Samples 

 of air taken from different parts of the room contained onlv 

 17.5 to 17.7 per cent, of oxygen, or from 3.2 to 3.4 per cent, 

 less than is present in normal air. The oxygen in the air 

 in the shaft of the well amounted to no more than 8.6 to 

 8.9 per cent., and other experiments confirmed the con- 

 clusion that the air in the storeroom w-as ordinary air 

 containing less than its proper proportion of oxygen, owin,:'' 

 to admixture with air deprived of its oxygen, which issuei 

 from the well shaft. The source of the impoverished air 

 from the well was finally traced to tunnelling operations 

 close by, in which compressed air was being used. This 

 air must have found its way through the soil wherever it 

 was sufficiently porous, and so into the shaft of the well, 

 and on its passage through the soil must have been deprived 

 of part of its oxygen by contact with some substance sucii 

 as pyrites. Evidence in support of the correctness of this 

 conclusion was furnished by the analysis of the mud from 

 another well shaft near the first. This mud was found to 

 contain pyrites, .and air left in contact with it for some 

 weeks was deprived of almost the whole of its oxvgen. 



Bologna Phosphorus 



In 1760, Canton made the discovery that when ovster 

 shells were calcined with sulphur in a crucible at a red 

 heat, there was produced a phosphorescent substance, which 

 he regarded as a form of phosphorus, but wdiich was really 

 an impure calcium sulphide. The so-called " Bologna 

 phosphorus " thus obtained has found a commercial use as 

 the luminous basis of phosphorescent paints. The 

 luminosity does not appear to be due to a slow process of 

 oxidation, since it has been found that a preparation that 

 had been sealed up in an air-tight tube for a centurv still 

 phosphoresced. Zinc sulphide has the same property of 

 being luminous in the dark. It has recently been observed 

 by Signor Vanino that the phosphorescent sulphides of 

 calcium or zinc can act upon a photographic plate in the 

 dark through a layer of black paper," but that all action 

 is checked by placing celluloid between the substance an^l 



the sensitive film. .Since radio-active preparations of lead 

 can act readily through celluloid, it would seem that the 

 action of the phosphorescent sulphides on the plate is not 

 due to /3 or 7 radiations (which can pass through celluloid), 

 but to traces of sulphuretted hydrogen, given off by ihe 

 sulphides, being capable of penetrating the paper, but not 

 the celluloid. Signor Vanino also finds that the presence 

 of calcium fluoride enables one to obtain an actively 

 phosphorescing sulphide at a much lower temperature than 

 is commonly used. The preparation may also contain a 

 large amount of inert suljslance, and only ;i sm.-ill propor- 

 tion of calcium sulphide, and yet he very luminous. 



The Identification of Horse-Flesh. 



One of the most difticult problems that the chemist is 

 called upon to solve is the identification of horse-flesh m 

 sausages or other flesh foods. It is well known that 

 enormous quantities of horse-flesh are eaten, chiefly in the 

 form of sausages, on the Continent, but in England the 

 strong prejudice against its use, the heavy penalty for 

 selling it without a notification, and the fact that there is a 

 ready sale abroad for broken-down horses, all tend to 

 render its use in English sausages unusual, .'\part from 

 the specific serum test (" Knowledge & Scientific News," 

 Vol. II., p. 86), w-hich has not as yet come into general 

 use, there are practically only two methods of chemical 

 examination, the determination of the characteristics of the 

 fat and the detection and estimation of glycogen or animal 

 starch. The fat of the horse is of a much more oily nature 

 than the fat of other domestic animals, and being composed 

 of more highly unsaturated glycerides, is capable of com- 

 bining with more iodine. But, although an examinatir>i 

 of the fat, especially of that deposited betw^een the muscular 

 fibres, is fairly conclusive in the case of pure horse-flesh, it 

 is unsatisfactory for mixtures, and more reliance is usually 

 placed on the glycogen test. Glycogen is identical in 

 chemical composition with ordinary potato starch or wheat 

 starch, but, unlike them, gives a red instead of the well- 

 known blue colouration with iodine. It is found in the 

 liver and blood of many animals, and may amount to as 

 much as 1.5 per cent, in the muscular fibre of the horse. 

 It is also present in the flesh of the mule, but not to any 

 extent in that of the ass. Herr Martin, who has recently 

 published the results of his experiments, finds that any 

 trace of glycogen in beef, veal, pork, or mutton soon disa])- 

 pcars from the flesh, whereas in the case of horse-flesh and 

 the flesh of foetal animals, it can be detected and estimated 

 for days after the animal w-as slaughtered. He attributes 

 the greater stability of glycogen in horse-flesh to the blood 

 of the horse having only a slight fermentative action as 

 compared with the blood of the ox or sheep. Herr Niebel, 

 some years ago, came to the conclusion that the reactio:i 

 with iodine was uncertain, for he found that glycogen was 

 rdso present in the flesh of dogs, cats, and very voung 

 calves, in the livers of cattle, and in meat extract. Herr 

 Bujard, again, found that the amount of glycogen and its 

 distribution through the body of the horse was influenced 

 by the food given to the animal, and by its state of health, 

 and considered that results obtained by this and similar 

 methods should only be regarded as a confirmatory test. 

 Another drawback is that the glycogen is destroyed by 

 smoking the flesh, and that the presence of ordin.ary starch 

 masks the red colouration that glycogen gives with iodine. 



GEOLOGICAL. 



By Edward A. Martin, F.G.S. 



The Enchanted Mesa. 



In the Journal of the Franklin Institute for June, there is 

 an extremely interesting paper by Professor Oscar Carter, 

 on the Plateau Country of the South-West, where is found 

 what is known as the Enchanted Mesa. The mesa is not 

 now inhabited, although sufiicient evidence has been ad- 

 duced to show that at one time, at any rale earlier than 

 1540, it was occupied by the Pueblo Indians, whose cliff 

 city of ,\coma is some three miles distant, and is built on 



