July 13, 1883.] 



SCIENCE. 



51 



through air, carbonic oxide, carbonic acid, and illu- 

 minating-gas. The sound is transmitted through a 

 tube two metres long, containing the gas experimented 

 upon, and the intensity is studied by noticing the 

 distance at which a sensitive flame ceases to be acted 

 upon by it. He finds that air and carbonic oxide 

 have the same transmissive power, air and illuminat- 

 ing-gas give very variable results, and carbonic acid 

 has a much greater transmissive power than air. A 

 table of results for air and carbonic acid is given. — 

 (Comptes reiiJM.s, April 30.) c. u. c. [44 



Experimental demonstration of velocity of 

 sound. — Grive.iux arranges a glass tube and a bar 

 of pine wood of equal length, so that the passage of 

 a pulse through either the column of air in the 

 tube or the wooden rod shall move one of two light 

 screws, and so break an electric contact. The cur- 

 rent from a battery is divided, and passes into the two 

 coils of a differential galvanometer; the light screw 

 resting on the end of the rod being placed in one 

 circuit, and a similar screw, resting on a membrane 

 closing the end of the tube, in the other. The le- 

 sistances are so arranged that the needle of the dif- 

 ferential galvanometer remains normally undeflected. 

 If a sound is produced by striking a drum, the needle 

 of the galvanometer is deflected in such a direction 

 as to show that the contact is broken by the move- 

 ment of that screw resting on the end of the wooden 

 rod, thus illustrating the greater velocity of the 

 sound-wave in wood than in air. — (Journ. phys.. 

 May.) c. R. c. [45 



ENGINEERING. 



Electric stop for steam-engines. — Mr. Tate, an 

 English engineer, has combined the Leclanch^ bat- 

 tery, an electro-magnet, an auxiliary steam-cylinder, 

 and a stop, to the closing of the stop-valve of the 

 steam-engine, if its sudden stoppage should become 

 necessary. It has been applied by Mr. Tate to the 

 driving-engines of his large woollen-mills in Bradford. 

 The mechanism consists of a weighted suspension 

 rod attached to the stop-valve by a bracket, and actu- 

 ated by a small steam-cylinder, the piston of which 

 is supplied with steam through a valve which is 

 opened by the action of the electro-magnet and the 

 weighted rod. The movement of this auxiliary en- 

 gine shuts the stop-valve of the engine in a small 

 fraction of the time usually required to close it by 

 hand. The wires of the battery are carried to vari- 

 ous parts of the mill, so that the engine can be 'shut 

 down ' at any instant, and from any one of a number 

 of promptly accessible points. This arrangement is 

 proposed to be attached to the engines of steam-vessels, 

 the wires being led to the bridge, and to other parts 

 of the vessel where the oflicers can easily reach the 

 button. — {London times, Oct. 21.) K. n. T. [46 



Forms of steamers. — Two vessels recently built 

 by the Messrs. J. & G. Thompson have been compared 

 to determine their relative economy as a means of 

 transportation as affected by a considerable differ- 

 ence in proportions. One was 390 feet long, 42 feet 

 beam, and drew IS feet of water : the second was 373 

 by 45 by 20 feet. The longer vessel had less fine ends 



than the broader ship. The former required 5,100- 

 liorse power to drive her 15 knots an hour, while the 

 latter only demanded 3.900. At 13 knots, the power 

 demanded was the same for both ; but at higher 

 speeds the difference became greater and greater, and 

 more and more in favor of the shorter, broader, but 

 finer ended vessel. The gain to be expected from 

 giving ships greater beam, and, at the same time, 

 finer ends, is expected to be observed in larger and 

 faster vessels. — {Mechanicn, May 26.) n. n. T. [47 



Efficiency of the steam-engine. — Professor R. E. 

 Werner, of the Technical high school at Darmstadt, 

 publishes a paper describing his tri.al of a compound 

 engine driving a mill in Augsburg. The engine has 

 an indicated power of 132 horses. The cylinders 

 have a proportion of 2.75 to 1 ; they are steam-jacket- 

 ed, as is the intermediate reservoir : the ratio of ex- 

 pansion is 14. The boilers carry a pressure of about 

 7 atmospheres, and the steam supplied contains 3 

 per cent water. The steam-jackets condense about 

 11 percent of the steam, and the cylinders demand 

 about 7 kilograms (15.4 lbs.) of steam per horse-power 

 and per hour, beside that condensed in the jackets. 

 This is about the amount required as a minimum in 

 the best-known English and American engines. In 

 this country, a very similar figure has been reached by 

 Corliss and by Leavitt. — (Zeitschr. ver. deutsch. ing., 

 May.) n. H. T. [48 



'Compound' locomotives. — M. Mallet com- 

 municates to the French society of engineers a note 

 from M. Borodine, giving the results of experiments 

 to determine the relative economy of the simple and 

 the compound system of engine for locomotives. The 

 engines experimented with were those designed for 

 the railway from Bayonne to Biarrit^ by M. Mallet, 

 The trials extended over a considerable period of 

 time, and the comparisons were made fairly com- 

 plete. The result showed the compound system to 

 have an economy of from ten to twenty per cent, 

 according to the conditions under which they are 

 carried out. The variation in the ratio of expan- 

 sion is very greatly restricted in the compound 

 engine. The use of the steam-jackets with which 

 the engines were provided did not prove to be of 

 .advantage. The expenditure of steam was greater 

 when they were in use than when they were shut 

 off. — (Mem. soc. ing. civ.) n. h. t. [49 



CHEMISTRY. 



iOrgonk:} 



Compounds of benzotricbloride tvith phenols 

 and phenylamines. — When a mixture of one mole- 

 cule of benzotricbloride and two molecules of phenol 

 is heated gently, O. Dobner finds that the following 

 reaction takes place : — 



C.H.on 



CjHsCCl. -^ 2 CeHjOH = C,n.CCI + 2 HCl. 



c.n.OH 

 The remaining chlorine atom is replaced by a 

 hydroxyl group when the product is heated with 

 water, forming dioxytriphenylcarbinol, — 



