190 



A'A TURE 



[June 22, 1905 



in the British Museum (Natural History), have been ex- 

 amined by the autlior for chitin. 



The conclusion drawn from the experiments is that the 

 general behaviour of the substance towards acids and 

 solvents is such that it is probably chitin, and this is con- 

 firmed by the fact that, after such treatment, it yielded, on 

 hydrolysis with concentrated hydrochloric acid, a strongly 

 reducing substance which is presumably glucosamine. 



" On the Magnetic Qualities of some Alloys not Con- 

 taining Iron." Bv Prof. J. \. Fleming, F.R.S., and 

 R. A. Hadfield. 



For the purposes of exact magnetic measurements two 

 homogeneous rings of regular form of alloys not containing 

 iron were made at tha Hadfield Steel Works, .Sheffield, and 

 sent to the Pender Electric Laboratory of University 

 College, London. These two rings were respectively 

 numbered No. 1871 and No. 1888/7. The ring No. 1871 had 

 the following composition : — manganese, 2242 per cent. ; 

 copper, 60-49 P^'' cent.; aluminium, 11-65 P^^ cent. There 

 is a certain amount of intermingled slag, probably 2 per 

 cent, or 3 per cent., mostly consisting of MnO and SiO, 

 and slight traces of other metals. Analysis showed that 

 there was present also : — carbon, 1-5 per cent. ; silicon, 

 0-37 per cent.; and iron, 0-21 per cent. Hence it may be 

 said that nothing but a trace of iron occurs in this sample 

 of alloy. The other ring. No. 18S8/7, had an approximate 

 composition : — inanganese, 18 per cent. ; copper, 68 per 

 cent. ; aluminium, 10 per cent. ; lead, 4 per cent. These 

 alloys unfortunately have poor mechanical properties and 

 are brittle and cannot be forged. Rings were cast from 

 the material and turned in the lathe to the desired form. 



From the observations the following conclusions are 

 drawn : — • 



(i) The alloy No. 1871, composed of copper, aluminium, 

 and manganese in the proportion mentioned above, exhibits 

 magnetic properties which are identical with those of a 

 feebly ferro-magnetic material. (2) The magnetisation (or 

 B, H) curve is of the same general form as that of a ferro- 

 magnetic metal such as cast iron, and indicates that with 

 a sufficient force, a state of magnetic saturation would 

 most probably be attained. (3) The alloy exhibits the 

 phenomenon of magnetic hysteresis. It requires work to 

 reverse the magnetisation of the material and to carrv it 

 through a magnetic cycle. (4) The material has a maxi- 

 mum permeability of 28 to 30, which is not greatlv inferior 

 to that of the values reached for cobalt or a low grade 

 of cast iron for small magnetic forces, and occupies a 

 position intermediate between the permeability of the ferro- 

 magnetic and the merely para-magnetic bodies, such as 

 liquid oxygen and ferric chloride. (5) The material 

 exhibits, therefore, the phenomenon of magnetic retentivity 

 and coercivity. It is not merely magnetic, but can be 

 permanently magnetised. 



The authors are led by these results to conclude that the 

 magnetic properties of this alloy must be based on a 

 certain similarity of molecular structure with the familiar 

 ferro-magnetic metals. 



Experiments on the magnetic qualities of the alloy No. 

 1888/7 give results similar to those of the alloy No. 1871. 

 For both alloys No. 1871 and No. 1888/7 the hysteretic 

 e.xponents are not very different, being respectively 2-238 

 and 2-288, whereas "the hysteretic constants are very 

 different, being respectively 0-0005495 and 0-000776. It is 

 clear, therefore, that both these alloys, although magnetic, 

 have far greater hysteresis than pure iron, nickel, or cobalt 

 for corresponding cycles of magnetisation. 



" Note Supplementary to a Paper ' On the Radio-active 

 Minerals.'" By the Hon. R. J. Strutt, F.R.S. 



In a paper read before the society on February 28, the 

 author directed attention to the fact that all' thorium 

 minerals, so far as could be ascertained, appeared to con- 

 tain uranium and radium. Since then he has examined 

 a number of additional minerals, in order to test the 

 induction further. The result has been quite confirmatory 

 of the original conclusion. The author, in this further 

 investigation, contented himself with determining the 

 thorium and radium, for it may now be considered proved 

 NO. i860, VOL. 72] 



that radium is a product of uranium, and it is much 

 easier to establish the presence of radium by its emanation 

 than to detect uranium by chemical analysis. The experi- 

 mental methods e.xplained in the former paper were 

 employed. The results are as follows : — 



ed of pure grains of 



, picked 



Mathematical Society, June 8. — Prof. A. R. Forsyth, presi- 

 dent, and temporarily Prof. W. Burnside, vice-president, in 

 the chair. — On the conditions of reducibility of any group 

 of linear substitutions, and On criteria for the finiteness of 

 the order of a group of linear substitutions : Prof. W. 

 Burnside. In the first of these papers it is proved that 

 a group of linear substitutions on a finite number of 

 symbols is reducible if, and not unless, one or more linear 

 equations holds between the coefficients of every substitu- 

 tion of the group. In the second paper it is shown that 

 in order that a group of linear substitutions may be of 

 finite order it is necessary that both the real part and 

 the imaginary part of every coefficient should lie between 

 two fixed assignable numbers, and this condition is 

 sufficient. — On a class of many-valued functions defined 

 by a definite integral : G. H. Hardy. The integral 



till 



is a many-valued function of x having no singularities 

 save .i; = o, and the behaviour of the function depends on 

 the character of a and \ as rational, algebraic or trans- 

 cendental numbers. In a number of cases the function 

 can be represented in the neighbourhood of the singular 

 point by a convergent combination of two divergent power 

 series. — Informal communications were made as follows ; — 

 The first principles of Cauchy's theory of functions : 

 G. H. Hardy. — On differential equations whose integrals 

 are expressible by partial quadratures : Prof. A. R. 

 Forsyth. 



Royal Astronomical Society, June 9.— Mr. \V. H. Maw, 

 president, in the chair.— The discordant values of the 

 principal elliptic coefficients in the moon's longitude : P. H. 

 Coweli — Determination of heat radiation from the moon : 

 the Earl of Rosse. The author had found that the lunar 

 heat varied with the phase, that it was negligible at new 

 moon, and attained its maximum at full moon. He con- 

 sidered it a surface heat, not regularly reflected, but 

 absorbed and re-emitted. Suggestions were made for 

 future observations during lunar eclipses. Prof. Turner 

 stated that the maximum at full moon might indicate 

 that some of the heat was reflected.— The diurnal vari- 

 ations of nadir and level of the Greenwich transit circle : 

 Astronomer Royal. The variation of the level has a 

 period of twenty-four hours, with a maximum about 6 a.m. 



