JVJ.Y 6, 18S3.] 



SCIENCE. 



19 



Bromide of potassium 1} ounces. 



Pyrogallic acid 2 ounces. 



Dissolve in distilled water 32 ounces. 



Add sulphuric acid (c. p.) . . . . li'O minims. 

 Add aqua ammonia (strongest) . . . :! ounces. 

 Add water to make up bulk to ... 40 ounces. 



The sulphuric acid and aqua ammonia should be 

 measured very exactly. Instead of three ounces of 

 crystals, two ounces of granular sulphite of soda may 

 be substituted to produce the same effect. Dilute a 

 sufficient quantity for one day's use as follows: for 

 ordinary purposes, one part in eleven ; for very short 

 exposures, one part in tliree to six; for over-exposed 

 plates, or in all cases where great intensity and con- 

 trast are desirable, one part in twenty. This devel- 

 oper may be used repeatedly if it is always returned 

 immediately to the pouring-bottle, which should be 

 provided with a tight-fitting rubber stopper. As long 

 as the solution remains transparent, it is good; but 

 when it looks muddy its use should be discontinued. 

 — {Pkilad. phut., Jane.) w. h. p. (6 



ENGINEERING. 



Mill-engines. — The Southwark iron foundry has 

 constructed for Messrs. Cheney Brothers of South 

 Manchester, Conn., a compound 'Porter-Allen" en- 

 gine, having steam-cylinders 12 and 21 inches diam- 

 eter, 2-feet stroke, to run at ISO revolutions per 

 minute. The power is given at 200 hoise-power. The 

 ratio of expansion is 16. The expenditure of water 

 was 18.5 pounds per horse-power and per hour. Of 

 this, 11.75 was accounted for by the indicator: the 

 rest was wasted by condensation in the sleam-cyl- 

 inders and by leakage. In these engines the low- 

 pressure cylinder is steam-jacketed, and the exhaust 

 from the high-pressure cylinder passes into an inter- 

 mediate reservoir, from which the large cylinder is 

 supplied. The reservoir acts as a separator for the 

 water carried in with the steam; and this water is 

 trapped off, and does not reach the low-pressure cyl- 

 inder. — (3/ec/iaiiics, May 19. ) r. h. t. [7 



Compressed steel. — Tests have been made at 

 the Watertown arsenal on cold-worked steel made 

 by Naylor & Co. at the Norway steel and iron works, 

 Boston, Mass. The elastic limit is raised from 26,.'>10 

 pounds per square inch (1,966 kgs. per sq. cm.), in 

 the hot-rolled bar, to 61,000 pounds (4,288 kgs.) in the 

 cold-rolled steel. The ultimate strength is increased 

 from 55,400 pounds (3,895 kgs.) to 10,420 (5,140 kgs.), 

 in one case, and to 81,890 (5,757 kgs.) in another. The 

 results of tests made at the mechanical laboratory of 

 the department of engineering of the Stevens insti- 

 tute of technology are given, showing the increase 

 due to cold rolling to be 70 per cent of the original 

 torsional strength with iron, and over 1.50 per cent 

 with soft steel. The resilience, or shock-resisting 

 power, was increased, in an average of three tests, 

 nearly 300 per cent in iron, and to double the latter 

 quantity in steel. — (Ilnd.) u. H. T. |8 



Time-fuze for artillery. — Col. Richardson, R.A., 

 finds that all the forms of time-fuzes at present in 

 use are unsatisfactory, since they depend for their 



accuracy on the length of time during which a given 

 column of composition burns: and this is a matter 

 which is difficult of control at the best. He proposes 

 to take advantage of the rapid and regular rotation 

 of the shell during its flight by which to work a 

 mechanism, which shall liberate a concussion-fuze 

 at any desired moment. — {Pmc. ray. artill. inst., 

 April, 1883.) c. F.. M. (9 



CHEMISTRY. 

 {Ilenernl, ijhyncal, and inorganic.) 



Basic sulphates of copper. — By continued boil- 

 ing of a solution of cuprie sulphate, S. U. Picker- 

 ing obtained a basic sulphate, to which he assigns 

 the formula 6CuO . 280, . SII^O. Precipitation 

 in the cold with potassic hydrate gave the basic salt 

 4CuO . SO3. — {Chem. news, xlvii. 181.) c. F. M. 



[10 



The hydrates of chlorine. — E. Maumene thinks 

 that the hydrate 01 . 10H,,0. mentioned by Faraday, 

 does not exist. Maumenfe obsen'ed the formation of 

 the hydrate 01 . 4H.,0, which crystallized in cubes, 

 and of the hydrate 01 . 711^0 in well-marked crystals. 

 With an excess of water, the hydrate 01 . 4H,0 is 

 converted into the form 01 . 12II.,0, which forms 

 orthorhombic crystals. — {Bull. soc. cliim., xxxix. 

 :3',tT.) c. F. M. [11 



Ammouiacal bromides and ozy-bromides of 

 zinc. — AVhen zinc oxide is dissolved with the aid 

 of heat in a solution of aminonic bromiile, G. Andr^ 

 states that the compound 3ZnBr,, . SNH^, . Hj,0 is 

 formed. This compound is completely decomposed 

 when boiled with a largo quantity of water, leaving 

 only the oxide. The compound 3 ZnBr^ . 4NH3 . HjO 

 is formed when the experiment is conducted in the 

 cold. On passing dry ammonia gas into a solution 

 of zinc bromide, it is absorbed, with the formation of 

 the product :3 ZnBr,, . 5NH, . II,,0. The compound 

 2ZnBr., . 5 XH , results when the ammoniacal bro- 

 mide 2ZnBr,, . SNH;, . 2 H,0 is heated. The follow- 

 ing oxy-bromides were prepared by methods similar 

 to those which give the oxy-chlorides: ZnBr, . 

 4Zn0 . 13H,0, ZnBr. . 4Znb . 19H,0, ZnBr« . 

 oZnO . 6H,6, ZnBr, . 6ZnO . SoH^O.—iliuU. aoc. 

 chim., x.xxix. :59S. ) c. F. m. [12 



Artificial hausmannite. — By heating manganous 

 chloride to the point of fusion for several hours, A. 

 Gorgen obtained crystals, on cooling, which possessed 

 .all the properties of the mineral hausmannite. — 

 {Comptes reniJus, xcvi. 1144.) r. f. m. [13 



Formation of stilphides by pressure. — W. 

 Spring submitted finely divided m.ignesiiim with the 

 amount of sulphur calculated for one atom to a press- 

 ure of sixty-five hundred atmospheres. The prod- 

 uct proved to be a homogeneous mass which gave 

 off hydric sulphide when heated with water to .50° or 

 60°. Zinc sulphide was formed by subjecting a mix- 

 ture of zinc and sulphur to the same pressure. Iron 

 united with sulphur, forming, probably, a polysul- 

 phide. Cadmium gave a yellow powder, from which 

 hydrochloric acid liberated hydric sulphide. Sul- 

 phides of aluminum, bismuth, lead, silver, copper, 



