366 



SCIENCE. 



[Vol. I., No. 13. 



distance for wliiob the eye is focused, appear curved. 

 Tlie explanation of the plienomeiion is essenlially the 

 same as lliat of ' Selieiner's experiment.' Tlie autlior 

 suggests tliat it may he employed in tlie construction 

 of an optometer. — '( P/liig. cuxhiv, xsx. 2S8. ) u. N. M. 



[760 

 Heat. 



Thermometry. — In a recent communication Prof. 

 Clevelaiiil Abiie lias reviewed the subject nf tlie de- 

 termination of the temperature of the air at a given 

 locality, and doscrilied an original device. Begin- 

 ning with the simple lianging of llie thermometer in 

 tlie open air, lie proceeded to describe and point out 

 the defects of the various metliods of exposure of tlie 

 past .and present, — the thenuonieter in llie shale, 

 the Glalsher screen, tlie .Stevenson screen and double- 

 louvre screens in general, the double melallic cylin- 

 der shelters of Jetinck and Wild, the silver-thimble 

 screen of Regnault, llie whirling thermometer of 

 Sau-;sure and others, and .Joule's method. The 

 method deviseil by himself in 1S05, and practised for 

 a short time at Pulhova, consisted in constructing a 

 very perfect louvre screen, within which were estab- 

 lislied black-bulb and bright- or silvo'ed-btilb ther- 

 mometers. One of these was greatly influenced by 

 radiations from the surrounding screen, and the other 

 very little: and the difference of their readings ena- 

 bled the effect of radiation to be computed and elimi- 

 nated. Provided the theory of the action of the 

 bright and black bulbs is perfectly understood, they 

 can be employed in conjunction by meteorologists 

 and physicists without a screen, and even in sun- 

 light. 



The formula used for reduction at Pulkova was 

 ta= ts + c{tb— U), 

 In which t„ is the temperature of the air, ts and U are 

 the readings of the bright-bulb and black-bulb tlier- 

 momeleis, ami c is a co-efficient to be determined 

 experimentally frn- each pair of instruments. Quite 

 recently Prof. William Ferrel has made a theoretic 

 invesligatio)i of the co-efficient, showing that it is not 

 strictly constant, but varies with the velocity of the 

 air-current passing the bulb^. Representing by Va and 

 n the radiating powers of the bright and black bulbs, 

 by B, I',', and li", certain constant co-efficients de- 

 pending on the size, conductivity, and specilic heat 

 of the bulbs, and by v the velocity, he writes the full 

 formula thus : — 



1 -f ^''o 



ta= t,+ 



ir + B"v 



— 1 



(fo - ts). 



1761 



— {Phil. soc. Wash. ; meeting March 24.) 



Electricity. 

 Determination of surface of ■winding. — F. 



Himstedt gives a method of determining experimen- 

 tally the wiadinvisjldche of a bobbin by suspending it 

 in the magnetic meridian, and comparing the deflec- 

 tion due to a given current with that due to another 

 current in a coil whose constants can be directly 

 measured. By hanging the two coils rigidly con- 

 nected upon the same suspension, and passing the 

 current lirst in the same and then in opposite direc- 

 tions through the coils, he obtains 



S_+ .s _ I' tan iji 



S — s ~ I tan <f' 

 where ^ represents the dedeclion when the current is 

 in the same direction. Tliis formula remlcrs neces- 

 sary only the measurement of four angles. The paper 

 of P. Kohlratisch which suggested this is given in 



full in Ann. phys. chem., iv. — {Ann. phijs. chem., 

 iii.) J. T. [762 



Telephony. — At a recent meeting of the Society 

 of telegraph engineers and of electricians, J, Munro 

 described some new forms of microplionie transmit- 

 ters. Among them was one consisting of two pieces 

 of wire gauze held together by a magnet. In another 

 form the mieroiihonic contact was between the links 

 of a sliort stretched chain. No iletails of practical 

 trials are given. Mr. Stroh described an experiment 

 in which he showed, by the use of a mirror and 

 screen, that, in the case of one carbon cylinder resting 

 across another, the upper one was raised j^, mm. 

 during microscopic contact. — {Electrician, March 

 17) J. T. [763 



The Ayrton and Perry erg-meter. — Professor 

 Perry ^dves a proof of the principle of the erg-meter, 

 which measures the work done by a current by moans 

 of its electro-magnetic retardation upon a pendiduin- 

 bob. — (ftiU) J. T. [764 



Conti's system for neutralizing induction. — 

 One of two parallel wires is bent uiion itself at one 

 point of its coui-sc into a long, rectangular loop. The 

 current in the outer side of tliis rectangle is opposite 

 to that in the straight part of tlie wire, and may be ■ 

 brought near enough to a neighboring line to neu- 

 tralize the mutual induction. — {Electr. reii., Feb. 

 2-t.) J. T. [765 



CHEMISTRY. 

 (Organic.) 



The hydroxylamine reaction. — Generalizations 

 of this reaction are still in progress in tlie laboratory 

 of V. Meyer. E. Niigeli obtaincil fi'om mesilyloxide, 

 mesityloxime (CsH,„ = NO 11) ; from phoron, phiu'on- 

 oxime (Cc,Hi4=N O H); from allylacetone, allylace- 

 toxirae (C|;Hln = ^^0 11); and from sttberono, suber- 

 oxime (C7H|2=NOH). Of still greater interest was 

 the formation from camphor of caniphornxinie, — 



C,„Hj„0 + NH„OH = H.O + t'loHjo = NOII. 

 This reaction is a strong indication of the ketone 

 character of camphor. Hydroxylannne was without 

 action upon borneol and menthol. With chloroform 

 the following reaction took place: — 



CCl. CI - C = NOH 



I -1-2NH,0H = 2HC1 +H20-t- I 



COH H -C = NOn 



Chlnroform. Monoclilorglyo.\iinG. 



Max Wittenberg and V. Meyer employed the hy- 

 droxylamine reaction to prove the constitution of 

 benzil aiul benzoin. If the formultie hitherto accepted 

 are correct, two molecules of hydroxylamine should 

 be absorbed by benzil, — 



QHs - CO NH.OH C„n, - C = NOH 



' + ' = 2H.,0 + ■ ■ I 

 CJij - CO NH,OH ■ CoHj - C = KOH 



and one molecule by benzoin, — 



C,,U, - CO CbHj - C = NOH 



I -I- NHoOH = H.O + I 



C„H3-CnOH ' C„H.,-CnOH 



On trial it was found that one molecule only of 

 hydroxylamine entered into the reaction in either 

 case. To niike sure that hydroxylamine acts the 

 same upon the group —CO— CO— as upon the group 

 — CO— Oil-,— , the leaction was tested with glyoxal, 

 with the followinti results: — 



HCO NH,OH nc = NOH 



I -I- " = 2n30 + I (glyoxirac), 



HCO NH,on no = noii 



Benzil cannot, therefore, be a substituted glyoxal. 

 These investigations will be continued in dilTerent 

 directions to "determine which of several possible 

 formulae represents its constitulion. — {Berichte 

 dentsch. chem. rjeseilsch., xvi. 4di, 600.) c. F. ii. [766 



