726 



SCIENCE 



[Vol. LVI, No. 1460 



ether-carbon tetrachloride, benzol-chloroform, alco- 

 hol-water, brine-water and other combinations are 

 suitable. The apparatus consists of a cylindrical 

 mixing chamber liSving for its floor a stopcock of 

 special design wMch connects with a thistle tube 

 and a spout. With the cylinder partly filled, a 

 drop or a fragment of the material to be tested 

 is immersed, and tlie specific gravity of the mix- 

 ture is then varied at will irathout agitation of 

 any kind by dropping the heavier component in 

 from above ox forcing the lighter component into 

 the cylinder from below until the mixture has the 

 same specific graraty as the material to be tested. 

 The specific gravity of the mixiture is then deter- 

 miued by Westphal balance or by a hydrometer 

 of special design. The design of the stopcock 

 permits the separated discharge of mixing cham- 

 ber and thistle tube into their respective con- 

 tainers so that the solutions may be used repeat- 

 edly or determinations made in series without dis- 

 charging the contents by removing the material. 

 The method is delicate, has a wide margin of 

 safety from error and the attaiinable accuracy 

 seems limited to the accuracy of the metihod ^ised 

 to obtain the specific gravitj' of the mixture. 



A new method for the control of thermostats: 

 D. J. and J. J. Beaver. A method for aecu- 

 Tately controlling the temperature of a thermo- 

 stat for long periods is described in which a very 

 small current, of the order of 10-n amperes, is 

 amplified by a vacuum tube sufliciently to actuate 

 .a magnetic relay. The circuit is so designed that 

 the chattering of the relay oan be prevented by 

 ■electrical metliods. The effect of an oscillating 

 point is obtained without an elaborate mechanism 

 and the back-lash at tlie mercury contact surface 

 is prevented by the use of iron wire for the eon- 

 tact point. A sensitive thermoregulator is 

 described which is made of nioaiel metal tubing 

 filled with mercury. A simple method of con- 

 necting glass to metal is described. 



Adiabatie calorimetry at high temperatures: 

 J. "W. Williams and Farkington Daniels. 

 Adiabatie calorimeti-y is possible at high tem- 

 peratures if sufficient precautions are taken to 

 prevent thermal leakage from the inner calori- 

 meter to the room. The construction of such a 

 calorimeter is described. The out«r bath, a 

 glycerine solution of ferric chlorids, is heated 

 electrolytieally. Thermail leakage along the re- 

 sistance thermometer is difficult to overcome, so 

 it is placed in the outer bath, a,nd readings are 

 taken when its temperature is ddemtieail with that 

 of the inner calorimeter as shown by zero reading 



on a sensitive thermocouple. The specific heats of 

 aniiline and nitrobenzene in the neighborhood of 

 100° have been determined. 



Black phosphorus: Claude Haines Hall, Je. 

 The author has collected and analyzed the some- 

 what extensive and complicated literature relating 

 to black phosphorus. He has shown that in 

 reality two distinct substances have been given 

 this name. The fio-st, discovered by Thenard in 

 1812, Is not a true allotropie modification but is 

 a colloidal suspension while the second, discovered 

 by Bridgmau in 1914, is a true modification. He 

 has devised an apparatus to extend Svedberg's 

 method of preparing colloidal suspensions to 

 phosphorus and has definitely prepared suspen- 

 sions of copper phosphide and mercury in phos- 

 phorus. The properties of these suspensions are 

 described. 



Notes on potassium chlorate: H. W. Moseley. 

 In this paper the following matters are presented : 

 first, the preparation of specimens of potassium 

 chlorate by altogether different and independent 

 methods; second, the details of the determination 

 of the melting point of the several specimens with 

 check results (the literature shows a variation of 

 40° in this constant), the composition of the bath 

 necessary for this measuremenit, 'and the fact of 

 no decomposition at the melting point; third, the 

 determination of the temperature of beginning 

 deeoniposition viitli a Study of the decomposition 

 reaction up to and includiug 500° C. 



Ozone: electrical preparation and analysis: 

 A. Silverman and Paul C. Saunders. Ozonizing 

 unit employed for the generation of ozone is a 

 modifieatiiou of the Berthelot apparatus. The 

 oxygen generator, purifying train, ozonizer, mano- 

 meter and analyzer are all parts of a single piece 

 of apparatus. All connections are of glass. The 

 parts of the unit are so constructed that all read- 

 ings can be made in a thermostat. Within the 

 Hmits of operation employed only O3 was ob- 

 tained. Yields have been calculated on the basis 

 of energy consumption. Concordant results have 

 been obtained under given sets of conditions. 

 Drawings accompany the article and lantern 

 slides will be employed in its presentation. 



Tlie analysis of gaseous mixtures of nitrogen 

 peroxide, nitric oxide, nitrous oxide and nitrogen: 

 Lowell H. Milligan and C. Herbert Quick. 

 The gases are conveyed by pure OOq through an 

 absorption train which removes NO2 and NO, and 

 then through NaOH soln, which takes out the 

 CO2 and over the surface of which the NqO and 

 N2 collect. The NoO is determined by slow-coon- 



