5o6 



KNOWLEDGE & SCIENTIFIC NEWS. 



[August, 1906. 



dition of metals when in a state of strain; and papers 

 on practical cnjjineering; subjects, such as Standardisa- 

 tion (Sir J. Wolfe Barry), Cilow Lamps (Sir W. Preece), 

 Monophase Electric Traction (C. F. jenkin), Turbines 

 (C. Ci. Storey), Waterproof Roads and Dust (Douglas 

 Mackenzie), will be read. 



Mr. Sidney Hartland will deal in his Presidential Ad- 

 dress to the Anthropolosfical Section with the growing 

 interest in anthropology and the growing recognition 

 of its practical importance by the colonising nations and 

 races. A discussion will take place in the section on 

 early British skulls, and Dr. C. S. Myers will contribute 

 a paper on measurements in the Egyptian Army. Dr. 

 Iladdon will speak on South African ethnology; Pro- 

 fessor Ridgeway on the origin of the fiddle; Professor 

 Flinders Petrie on Egyptian discoveries in 1906; 

 and there are various papers on Anglo-Roman and 

 Anglo-Saxon remains. 



Professor Gotch's address to the Physiologists is one 

 of the most important contributions to controversy 

 during recent years, and states very frankly his posi- 

 tion with regard to the subject of " vitalism " in 

 physiological science. It is the most arresting state- 

 ment of opinion since Dr. Japp's address on the 

 " Nature of Life " some years ago at the Bristol meet- 

 ing. A discussion is to be opened in this section on 

 the physiological value of rest, and another on minimum 

 diet values. The Chemical Section will co-operate in 

 this discussion. 



Professor F. W. Oliver, Quain Professor of Botany 

 at University College, London, .will deliver the address 

 to the Botanical Section, taking for his subject " The 

 Seed, as a chapter in Evolution." Three topics have 

 been chosen by the section for di.scussion : — (i) Some 

 aspects of the present position of Palaeozoic botany will 

 be dealt with by Dr. D. H. Scott, F.R.S., and the 

 conditions of growth of Carboniferous plants by Pro- 

 fessor F. E. Weiss and MLss M. C. Stopes. (2) The 

 nature of fertilisation and kindred problems, at a joint 

 session with Section D (Zoology). (3) The phylogene- 

 tic value of the vascular system of seedlings. Mr. 

 A. G. Tansley and Miss E. N. Thomas will open the 

 proceedings, while Professor Jeffrey, of Harvard, 

 Messrs. A. W. Hill, T. G. Hill, and Miss Ethel Sargant 

 are expected to contribute by papers or otherwise to 

 the discussion. 



I^rofessor Michael E. Sadler will deliver the Sec- 

 tional Address on Education, and the proceedings of 

 the section will be rich in discussions on " Health in 

 .Schools," the "Curriculum of Primary Schools," and 

 " The Teaching of Modern Languages." 



Mr. A. L. Bowley will preside over the Section of 

 Economics and Statistical Science, and will take for 

 the subject of his address the importance of true 

 scientific method in statistical research. 



Mr. Chester Tenn.^nt, of Dawson, in the Yukon, furnishes 

 us with some curious particulars on the things that happen 

 when the mercury in the Fahrenheit thermometer goes to 

 60 deg. or 70 deg. below freezing. The steel of edged tools 

 becomes .so brittle that it will break almost as readily as 

 glass under sudden strain or shock ; spikes of nails used 

 in the wooden-built houses contract ; coal oil begins to 

 thicken and solidify till it assumes the consistency of lard ; 

 and a lighted lamji left out in the cold goes out in about 

 .-m hour because of this reason. Every stovepipe in the 

 lownship throws out a great cloud of steam and vapour, 

 .ind a consequent white grey mist, or haze, remains per- 

 manent in the atmosphere, so that there is always a sort of 

 fi-o/en fog in the day time. Even people exhale this fog, 

 like locomotives, and the breath roars out like a mild jet 

 of steam. 



Photography. 



Pure and Applied. 



By Cn.\PM.^N JoNiis, F.I.C., F".C.S., &c. 



Ozohrome. — This curious word is derived from 

 "ozone " and "bromine," though it indicates a process 

 with which ozone has nothing to do, and bromine very 

 little. It is a method recently patented by Mr. 'ITiomas 

 Manly (who, a few years ago, introduced the ozotype 

 pr(KX!ss), by which a bromide print is made to furnish 

 one or several carbon prints. This means that the 

 facilit)' of making a bromide print either by contact or 

 enlarging methods, necessitating only a few seconds' 

 exposure to artificial light, may be combined with the 

 advantages of carbon or pigment prints with their 

 permanency and the wide choice of colours that they 

 permit. Indeed, the new method presents notable ad- 

 vantages as compared with the ordinary carbon process, 

 for not only is daylight unnecessary for the exposure, 

 but the print is not laterally reversed though there is 

 no double transfer, and in one modification no transfer 

 at all. The principles involved are very simple. Tlie 

 bromide print consists of a metallic silver image in a 

 gelatine film. Silver is in many ca.ses a very efficient 

 reducer, and by bringing into contact with it a pig- 

 mented gelatine film sensitised with a bichromate, the 

 silver, directly or indirectly, reduces the chromate, 

 much as exposure to light would, to a chromium com- 

 pound which renders the gelatine insoluble. 



The practical details riui on the following lines : 

 \ bromide print, which may be an old one, but must 

 have been thoroughly washed, is soaked in a formaline 

 solution for a few minutes to harden the gelatine, and 

 washed. The carbon tissue or 'pigment plaster" th.it 

 is to be used is soaked till limp in a solution that con- 

 tains an alkaline bichromate, fcrricyanide, and bromide, 

 while the bromide print is soaked in water, and the 

 two squeegeed together. If one print only is required, 

 after a few minutes the print is plunged into hot water 

 and developed in the same manner as a single transfer 

 carbon print. But if desired, the same bromide print 

 will furnish several carbon prints, by plunging the 

 original with the carbon tissue squeegeed to it into cold 

 water, separating them gently, and then treating the 

 carbon tissue exactly as if it had been just exposed to 

 light in ordinary carbon printing. The short contact 

 with the original is equivalent to the otherwise 

 necessary, and often prolonged, exposure to daylight 

 under the negative. The silver of the bromide print is 

 changed intO' a silver salt, but irnmersion in an ordinary 

 developing solution reduces it tO' the metallic state, and 

 so it can be used over and over again. It seems that all 

 carbon tissue is not suitable, and that a specially soluble 

 kind is supplied by the patentee. Full working details 

 will probably be obtainable before this is published, 

 together with modifications and other applications of 

 the process. 



This process seems, on the f;ice of it, to have so much 

 to commend it that the essential difference between 

 it and carbon printing by the ordinary methods must 

 not be lost sight of. Carbon printing, as hitherto 

 practi.sed, is a printing-out process, and the charm of a 

 carbon transparency, as well as its reliability for repro- 

 duction purposes, lies largely in this fact. Probably no 

 method gives a more exact representation of the nega- 

 tive, for the possibilities of altering the gradation by 

 accident or design arc hardiv worth consideration. But 



