iHh ALUM 'A 7 JOURNAL. 



215 



possess a very bitter taste, 

 tetrazolium chloride, 



N— NPh 



y 



Diphenyl 



HC 



N=N< 



Ph 



•CI 



which may be taken as a typical salt 

 of the series, crystallizes in color- 

 less • radiating groups of needles 

 very sensitive to light, which renders 

 them yellow. The aqueous solution yields 

 a flesh-colored precipitate of chloroplati- 

 nate with platinum chloride, and the 

 double salt may be crystallized from hot 

 water. A crystalline double chloride is 

 likewise produced with gold chloride. 

 The addition of a soluble nitrate or iodide 

 •causes the precipitation of the difficulty 

 soluble nitrate or iodide of the base. A 

 solution of iodine in potassium iodide pre- 

 cipitates an iodine addition product, 

 which can be crystallized from alcohol in 

 beautiful brown tabular crystals exhibit- 

 ing a violet reflection. The parent base 

 is produced in solution upon the addition 

 of silver oxide, silver chloride being like- 

 wise formed. The chloride is reduced 

 by ammonium sulphide to a compound of 



the constitution: 



N— NHPh 



/ 

 HC 



\ 



N=NPh 



a substance which Prof. v. Pechmann 

 has previously described, and which 

 is interesting as forming the start- 

 ing point for the preparation of the 

 new series. For the chloride may at 

 once be prepared from this latter sub- 

 stance by oxidation with amyl nitrite 

 and hydrochloric acid. The substance 

 is readily prepared by the action of di- 

 azobenzene chloride upon malonic acid, 

 constituting the insoluble product of the 

 reaction. It is of considerable interest to 

 observe that the main product of the dry 

 distilation of diphenyl tetrazolium chlor- 

 ide is azobenzene. — Nature. ♦ 



Photographic Notes. — Infinitely Rapid Mo. 

 tions and Photography. — On Saturday, March 

 9, at the Royal Institution, Lord Rayleigh, in 

 lecturing upon the multitudinous motions of the 

 waves of the sea, and the forces which govern 

 them in their phases, as revealed by the re- 

 searches of Stokes, Thomson, himself, and 

 others, spoke of waves upon the surface of 

 water too small and rapid to be seen by the eye. 

 These, he explained, can only be made visible, 

 and apparently slowed down so as to be appre- 

 ciated, by means of instantaneous photography, 

 or by a series of instantaneous optical projec- 

 tions P^ach flash of light, such as that of the 

 electric spark, makes the object appear to stand 

 still for a moment in one of its phases, and the 

 flashes must be so timed as to reveal each phase 

 so that they blend slowly, and the whole ap- 

 pears to be moving so slowly that the nature of 

 the motion can be seen. He projected an en- 

 larged image of a vibrating tuning fork upon 

 the screen, and its prongs appeared fuzzy from 

 the rapidity of the motion, but when the pro- 

 jection was performed by properly timed flashes 

 of light, he so slowed down the apparent mo- 

 tion, that each prong appeared to make but one 

 vibration in about two seconds, so that the 

 nature of its motion could be seen with ease. 

 He then projected upon the screen the photo- 

 graphs he took three years ago of bursting soap 

 films, each taken by the light of an electric 

 flash lasting less than one-millionth of a second. 

 The soap films were broken bv means of letting 

 a bullet, wetted with alcohol, fall through 

 them ; a dry bullet would go clean through 

 them, perhaps, a dozen times without breaking 

 them. The greatest difficulty in the work was 

 in the mechanical arrangements, to so time the 

 flash that it should occur just as the bullet had 

 passed through the film. The photographs 

 were good ones, showing the falling bullet, and 

 the torn and thickened edges of the br< ken 

 film, as well as some little attached filaments of 

 liquid beads of soap solution. — Photography. 



Tests for Trional. — Pure trional forms color 

 less, odorless crystals in thin lamellae, soluble 

 in 300 parts of cold water, easily soluble in ether 

 and alcohol, and melting at 76.5°C. Mixed 

 with charcoal and heated carefully, it gives off 

 the odor of mercaptan. The aqueous solution 

 should give no odor on boiling. After cooling 

 and filtering, it should give no turbidity with 

 barium nitrate, or silver nitrate. It should not 

 decolorize solution of potassium permanganate 

 — Pharni. Post. 



