214 



NA TURE 



[June 30, il 



special advantages claimed for this paper is that the several 

 difficulties involved in the working of ordinary papers are 

 removed. The chief simplification is in the fact that a dark 

 room may be entirely dispensed with, all operations being per- 

 formed in an ordinary room lit in the usual manner. The paper 

 is described as being coated with a chloro-bromide emulsion, 

 and it is owing to the extreme slowness of this that a special 

 non-actinic illumination is unnecessary. Of course, care is 

 wanted, and direct light should not be allowed access to the 

 print ; but in an ordinary room, lit by two windows at 

 middle of day, perfectly clean whites may be obtained by turn- 

 ing the back to the window, and developing in the shade thus 

 produced. 



Again, no great amount of apparatus is required, not even a 

 printing frame ; development is very efficiently performed on a 

 sheet of glass, applying the developer with a pledget of cotton- 

 wool or a mop camel-hair brush. 



The exposure for contact printing from an average negative 

 varies from 1-3 seconds for diffused daylight, to 30-120 seconds 

 to a gas-burner at 6 inches distance. A point that might with 

 advantage be added to the instructions for use, is the great con- 

 venience of magnesium ribbon as an illuminant. This is being 

 brought forward by many leading plate and paper makers, and 

 deservedly so. The light of burning magnesium is one of the 

 most intense illuminants at present known ; and as a great part 

 of the light is concentrated in the blue and violet regions of the 

 spectrum, the parts most effective on a silver emulsion, this 

 gives the light a high efficiency. From 1-3 inches of ribbon, 

 burnt at from 8-12 inches distance, will be found to give satis- 

 factory exposures. Another point in favour of using magnesium 

 is the ease of firing it, all the extra articles needed being a box 

 of matches. 



It might be worth while to make the gelatine, &c., which forms 

 the basis of the emulsion, more insoluble than it appears to be 

 from, the samples tested, as many people find it convenient to 

 dry prints quickly, and if the paper has not been specially 

 treated, there is danger of blisters or of complete melting of the 

 film. The paper is obtainable in several varieties of surface 

 and suitability for different purposes. 



Another suggestion, not mentioned in the circular issued, may 

 perhaps be made as likely to extend its popularity. It is that 

 the paper may be toned with any of the usual toning baths for 

 bromide paper, the one made with copper sulphate and potassium 

 ferricyanide, giving reddish-brown tones, being very suitable. 



One of its good qualities is the ease of maintaining pure whites ; 

 and this will no doubt lead to its extensive use for copying pur- 

 poses, as both the negative and positive may be made on the 

 paper. For scientific workers, as well as pictorial photographers, 

 the paper will doubtless prove a great boon. 



From its extreme simplicity of manipulation, moderate price, 

 and general high quality, the paper ranks high among silver 

 emulsion printing papers. 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE. 



Dr. Richard Abegg, privat-docent in physical chemistry 

 at Gottingen, has been promoted to the rank of professor ; Dr. 

 Oswald Lohse, observer in the Potsdam Astrophysical Observ- 

 atory, has also been promoted to a professorship ; Dr. Bohmig, 

 privat-docent in zoology at Gratz, has been appointed assistant 

 professor ; Prof. Kalkowsky, of the Technical High School in 

 Dresden, has been appointed director of the geological and 

 prehistoric museum there. 



On Wednesday in last week, the Duke of Devonshire opened 

 the new Christie Library at the Owens College, Manchester, and 

 laid the foundation of the Whitworth Hall, another addition to 

 the college buildings. The library is the gift of Mr. R. C. 

 Christie ; and the expense of erecting the Whitworth Hall will 

 be met by the sum of 50,000/. received by Mr. Christie as one 

 of the residuary legatees of the estate of the late Sir Joseph 

 Whitworth, and since paid by him to the Treasurer of Owens 

 College. 



It is but rarely that an issue of Science appears without the 

 announcement of one or more gifts to educational and scientific 

 institutions in the United States, or for the advancement of 

 learning. The following are among the donations recently 



NO. 



1496, VOL. 58] 



announced : —By the will of the late Dr. Elizabeth H. Bates, 

 of Port Chester, N.Y., the University of Michigan will receive 

 125,000 dollars, the income from which is to be used in estab- 

 lishing a chair for the diseases of women and children, to be 

 known as the Bates professorship. — The will of the late Mrs. 

 Annie S. Paton, of New York, leaves 100,000 dollars to Prince- 

 ton University, subject to an interest for life of her two sons. 

 The bequest is to found a fund for an endowment for Paton 

 lectureships in ancient and modern literature. — It is said that 

 Mrs. Phoebe Haarst will erect a building for mining engineering 

 for the University of California at a cost of 300,000 dollars. — 

 A building for the College of Agriculture of Ohio State Uni- 

 versity has been completed during the present year at a cost of 

 70,000 dollars. — The will of the late Mr. Felix R. Bonnet, of 

 Pittsburg, Pa., provides that, upon the death of his widow, 

 300,000 dollars shall go to the Western Pennsylvania Univer- 

 sity for the endowment of scholarships. — A donor, whose name 

 is withheld, has subscribed 25,000 dollars for Barnard College in 

 case the 100,000 dollars needed to liquidate the debt on the 

 College are subscribed by October 3. 23,000 dollars had 

 previously been subscribed. — Hobart College, Geneva, N.Y. , 

 has received 6000 dollars for a scholarship by the will of Mrs. 

 Augusta M. Williams. — Mr. Philip D. Armour has given an 

 additional endowment fund of 500,000 dollars to the Armour 

 Institute of Technology, Chicago. He had previously given the 

 Institute an endowment of 1,500,000 dollars. — Mr. Washington 

 Duke has given 100,000 dollars to Trinity College, Durham, N.C., 

 which makes the total amount of his gifts to the College 

 425,000 dollars. — Dr. D. K. Pearsons, who has assisted so many 

 smaller colleges, has offered to give the Salt Lake College, of 

 Salt Lake, Utah, 50,000 dollars, on condition that its officers 

 raise 100,000 dollars more within a year. — Dr. George W. Hill 

 has been appointed lecturer in celestial mechanics in Columbia 

 University, Miss Catherine W. Bruce having given 5033 dollars 

 for this purpose. 



SOCIETIES AND ACADEMIES. 

 London. 



Royal Society, May 26. — " On the Kathode Fall of 

 Potential in Gases." By J. W. Capstick, M.A., D.Sc, Fellow 

 of Trinity College, Cambridge. Communicated by Prof. J. J. 

 Thomson, F.R.S. 



Hittorf and Warburg have shown that when an electric cur- 

 rent passes through a tube containing a gas at a pressure of a 

 few millimetres, the fall of potential along the greater part of 

 the tube varies with the pressure of the gas and the current 

 strength, but in the immediate neighbourhood of the kathode 

 there is a fall which is constant in amount provided the negative 

 glow does not cover the whole electrode, or extend to the walls 

 of the tube. It seems likely that this kathode fall will prove 

 to be connected with other constants of the gas, and the aim of 

 the present investigation was to find such a connection by 

 measuring the kathode fall in a compound gas and its con- 

 stituent elementary gases. The gases used were water vapour, 

 ammonia, and nitric oxide and their constituents. 



No difficulty was experienced in measuring the fall in the 

 elementary gases, and the separate readings for any one gas 

 showed good agreement. It proved, however, a very difficult 

 matter to get a constant current to pass through the compound 

 gases. Many months were spent in a fruitless attempt to find 

 what conditions determine the constancy of the current, and 

 since the kathode fall is not constant when the discharge is 

 intermittent, very few measurements could be made on the com- 

 pound gases. 



The values in volts ultimately found for the kathode falls were 

 as follows : — 



Hydrogen 

 Nitrogen 

 Oxygen 



Water vapour .. 

 Ammonia 

 Nitric oxide .. 



232 

 369 

 469 

 582 

 373 



Warburg had previously determined the fall in hydrogen and 

 nitrogen. For the former, he found 300. For atmospheric 

 nitrogen containing argon, he found 232. The present experi- 



