Chemistry and Physics. 237 



A. Wkoblewski has devised a method of evaporation by which 

 this difficulty is overcome. He places the solution from which 

 crystals are to be obtained in a cylinder the bottom of which is 

 closed with a parchment membrane, while the top is corked and 

 provided with a water trap. Evaporation takes place through 

 the membrane the lower side of which is exposed to air artificially 

 dried with calcium chloride. In the case of readily diffusible 

 salts a certain amount of dry crystals is formed upon the external 

 surface of the membrane, but this does not take place with dilute 

 solutions. Crystallization takes place within the cylindrical ves- 

 sel without the formation of crusts. The method is particularly 

 recommended for the crystallization of proteids. — Zeitschr. phys- 

 ical. Chem., xxx vi, 84. h. l. w. 



8. On the velocity of the ionized phosphorus emanation in the 

 absence of electric field \ by C. Bartjs. (Communicated.) — In 

 Science (Feb. 9, 1900) I communicated a series of data on the 

 absorption of the emanation from phosphorus, in tubes of dif- 

 ferent diameter (2r) and material. I have since brought my 

 results together and am now able to compute the velocity, k, of 

 the ionized particle absolutely. I find k =2*65 ( V/rx)ln V/V , 

 where I 7 ' and V are the liters per minute of air saturated with 

 phosphorus emanation needed to retain a field of constant color 

 in the steam tube, for lengths x and zero, respectively, of the 

 absorption tube of radius r. 



The results are for tubing of gray rubber, 2r="64 cm , ^=-28 cm /sec; 

 pure rubber, 2r='35 cm , &=-32 cm /sec; lead, 2r='63 cm , &=-25 cm /sec; 

 lead, 2r= -32 cm , k= '30 cm /sec ; glass, 2r= -29 cm , k— •2'7 cm /sec. 

 These data show no relation to diameter or material. 1 conclude 

 that the ionized region is under a kind of osmotic pressure such 

 that for highly saturated phosphorus emanation the velocity of 

 particles is about 3 millimeters per second. This small velocity, 

 it will be noticed, is associated with large viscous resistances, so 

 that the pressures are not necessarily small. 



9. The Thermo-chemistry of the Alloys of Copper and Zinc ; 

 by T. J. Baker, B.Sc, King Edward's School, Birmingham. 

 Read January 17, 1901, before the Royal Society of London.* 

 (Abstract.) — The heats of formation of a number of alloys of 

 copper and zinc, containing those metals in very diverse propor- 

 tions, have been ascertained. The method consists in finding the 

 difference between the heats of dissolution, in suitable solvents, 

 of an alloy and of an equal weight of a mere mixture containing 

 the metals in the same proportion. 



The first series of experiments was made with an aqueous solu- 

 tion of chlorine as solvent. Its application was limited to those 

 alloys containing less than 40 per cent of copper, as it was impos- 

 sible to obtain those richer in copper in a sufficiently fine state of 

 division to enable them to dissolve. The results, though not 

 altogether satisfactory, showed that the heat of dissolution of an 



* Advance proof from the author. 



