So 



NATURE 



May 26. 1S92 



and weighed. The chlorine contained in a third portion 

 was determined by means of silver nitrate in the ordinary 

 manner. From the numbers so obtained the equivalent 

 of masrium was calculated. A pure preparation of 

 masrium oxalate was also obtained by precipitating 

 the neutral solution of the chloride with ammonium 

 oxalate, masrium oxalate resembling the oxalate of 

 calcium in being insoluble under such conditions. The 

 precipitated oxalate was washed, dried, and ignited in 

 a combustion tube whose forward end was filled with 

 copper oxide, when the salt was decomposed with elimin- 

 ation of its water of crystallization, which was absorbed 

 and weighed in the usual manner. The residual oxide 

 was also weighed, and the oxalic acid, in another quantity 

 of the salt, was determined by means of a standard 

 solution of potassium permanganate. The crystals of the 

 oxalate were thus found to contain 5270 per cent, of 

 masrium oxide, 15 "85 per cent, of oxalic anhydride, and 

 31*27 per cent, of water. 



From the whole of the analytical data yet obtained, 

 assuming, as the reactions of the salts would indicate, that 

 masrium is a divalent element^ the atomic weight would 

 appear to be 228. An element of atomic weight about 

 225 is, indeed, required to occupy a vacant place in the 

 periodic system in the beryllium-calcium group, and 

 masrium appears likely to be the element in question. 



Masrium has only yet been observed to combine with 

 oxygen in one proportion, to form the oxide MsO. 

 Masrium oxide is a white substance much resembling the 

 oxides of the lime group. The chloride, MsCla, is obtained 

 upon evaporation of a solution of the oxide or hydrate in 

 hydrochloric acid. The nitrate, Ms(NO^)._,, crystallizes 

 from 50 per cent, alcohol, and the crystals contain water, 

 the amount of which has not been determined. The 

 sulphate, MS.SO4 . 8H2O, is a white salt which crystallizes 

 badly from water, but which separates in well-developed 

 crystals from 50 per cent, alcohol. It combines with 

 sulphate of alumina to form an alum, also with potassium 

 sulphate to form a double sulphate. The oxalate above 

 referred to, MSC2O4 . 8H2O, is a white salt, soluble in 

 acetic acid, and also in excess of masrium chloride. 



The most important reactions of the salts of masrium, 

 as far as they have yet been studied, are the following. 

 Sulphuretted hydrogen produces no precipitate in pre- 

 sence of hydrochloric acid, but yields a white precipitate 

 in presence of acetic acid. Ammonia precipitates the 

 white hydrate of masrium from solutions of the salts ; the 

 hydrate is insoluble in excess of ammonia. Ammonium 

 sulphide and carbonate produce white gelatinous pre- 

 cipitates, likewise insoluble in excess of the reagents. 

 Ammonium phosphate yields a white precipitate of phos- 

 phate. Caustic alkalies precipitate the hydrate, but the 

 precipitate is readily soluble in excess of the alkaline 

 hydrate. Potassium ferrocyanide produces a white pre- 

 cipitate which is soluble in excess of masrium chloride, 

 but not in dilute hydrochloric acid. Potassium ferricyan- 

 ide yields no precipitate. Potassium chromate precipi- 

 tates yellow chromate of masrium, which is soluble in a 

 further quantity of masrium chloride. Potassium tartrate 

 yields a white tartrate precipitate which dissolves in ex- 

 cess of the reagent, but the solution is not reprecipitated 

 by the addition of ammonia. 



Metallic masrium has not yet been obtained. Attempts 

 to isolate it by heating the chloride with sodium under a 

 layer of common salt, and by the electrolysis of a solution 

 of the cyanide proved unsuccessful. The chloride, more- 

 over, is not sufficiently volatile to permit of its vapour 

 density being determined. 



From the above interesting reactions, however, it will 

 be evident that masrium possesses a strong individuality, 

 although on the whole behaving somewhat like the metals 

 of the alkaline earths and those of the zinc group. Further 

 work will doubtless afford more definite information con- 

 cerning its nature and properties. A. E. Tutton. 



NO, I I 78, VOL. 46] 



ON A NEW METHOD OF VIEWING 

 NEWTON'S RINGS. 



IF we observe the reflection of a rectangular strip of 

 any opaque substance (A) about \ inch wide in a 

 piece of plate glass 0/ about the satne thickness, it appears 

 thus :— 



Az 



Aj A^ being the reflections caused by the upper and lower 

 surfaces of the glass respectively. 



If a second glass plate, of the same thickness, be added 

 beneath the first, there is a third reflection (A4) added 

 below Aathus, drawing only the reflections for simplicity's 

 sake : — 



Ax 



Az 



A4 



Now if the upper slab of glass h^ gradually raised above 

 the lower, the opaque strip remaining in position, the re- 

 flection A;, (Fig. 2), which generally exhibits traces of 

 colour when plate glass is used, splits up into two (A^ A3), 

 thus :— 



Az 



^3 



A4 



Thus it is proved that A^ (Fig, 2) is the resultant of the 

 reflections of the strip by the lower surface of the upper 

 plate, and the upper surface of the lower plate (Ao and 

 A3, Fig. 3, respectively). 



In saying that Ai is the reflection of A caused by the 

 top surface, we mean that light which would fall on that 

 surface and be reflected to the eye is prevented from so 

 doing by the presence of A ; and so with respect to the 

 other reflections : thus, if any one of the reflections is 

 not perfectly dark, we can assert that the light seen in 

 it is at any rate not due to reflection (for the first time) 

 at the corresponding surface ; e.g. A4 (Fig. 2) appears 

 anything but dark, and we may assert that the light seen 

 in it is not reflected from the bottom surface of the lower 

 plate (at all events for the first time). 



Now by means of two similar rectangular strips A and 

 B, placed with their long sides parallel to the surface of 

 the glass, B being further from the observer and from the 

 top plate, it is very easy to arrange them so that B4 — 

 the reflection of B in the lower surface of the lower plate — 



