4:80 Scien tific In telligence. 



At least 9 molecules of KI must be added for one of HgO, and 

 in practice it is advisable to use a somewhat larger proportion, 

 as for example, 10 cc of 60% KI solution for 0.4 g of HgO. As 

 soon as the oxide has dissolved the mixture is titrated with the 

 acid solution to be standardized with use of methyl ora,nge, 

 phenolphthalein, or methyl red as indicator. The yellow oxide 

 can usually be bought pure, but it can be prepared by dissolving 

 100 g of mercuric chloride in 1 1. of warm water, cooling, and 

 then adding with stirring 625 g of 6.4% NaOH solution. The 

 precipitate is collected, washed until the washings are no longer 

 alkaline to phenolphthalein, air-dried, and then stored in black 

 glass bottles. — Zeitschr. analyt. Chem. Ivi, 177 (through C.A.). 



H. L. w. 



5. A New Oxychloride of Tin. — Harry F. Keller has exam- 

 ined some brilliant tabular or acicular crystals found in cavities 

 in a lenticular piece of metallic tin from an Indian burial mound 

 on Hogtown Bayou, Florida. The crystals were easily crushed 

 to a chalk-white powder, which on heating in the closed tube 

 melted, turned dark, and gave off acrid fumes without a trace 

 of water. The substance gave qualitative tests for tin in the 

 stannous state and for a chloride. A quantitative analysis, made 

 necessarily upon a small quantity, amounting to about 0.2 g, 

 gave results corresponding fairly well with the formula 

 SnCU.SnO. No reference to the ' existence of an anhydrous 

 stannous oxychloride was found in chemical literature. No 

 satisfactory explanation of the occurrence of the crystals in the 

 cavities appears to be given, for the suggestion that some 

 chloride solution had access through an opening at the surface 

 does not account satisfactorily for the production of an anhy- 

 drous compound. — Jour. Amer. Chem. Soc, xxxix, 2354. 



H. L. w. 



6. Equilihrium Temperature of a Body Exposed to Radia- 

 tion. — This problem is discussed in a very lucid and interesting 

 account recently published by Ch. Fabry. The general equa- 

 tion of thermal equlibrium of a small body isolated in free space 

 is derived in the following manner. The size of the body is 

 assumed to be such that its temperature T is uniform through- 

 out. S and s denote respectively the area of the surface of the 

 body and the cross-section of the beam of intercepted radiation. 

 For brevity, put S/s = r]. The absorbing properties of the sur- 

 face are defined by the absorbing power a which is a function 

 of the wave-length A: a = (/)(A). The radiation received by the 

 body is supposed to consist of waves that are sensibly plane. 

 It is defined by the curve connecting the energy with the wave- 

 length : E :=^{X). That is, E - dX means the power which each 

 square centimeter receives from radiations comprised between 

 A and X -{- d X. It is also necessary to introduce the radiation 

 formula for a black body, since this gives, for each temperature, 

 the curve of energy of radiation for unit surface : B ^=z F {X, T). 



