October 2, 19 19" 



NATURE 



95 



hexahydro-benzol in bulk, by hydrogenation of 

 benzene, is as yet in its infancy, but has a certain 

 future owing to the utility of the product as a 

 volatile fuel for internal-combustion engines. The 

 fact that it is a single compound gives it marked 

 advantages over petrol as a fuel for air transit, 

 since the variability of petrol is a distinct draw- 

 back in the case of a fuel upon which such rigo- 

 rous demands are necessary. 



The development of the fine chemical industry 

 in this country involves also an extended use of 

 catalytic reactions. The successful production of 

 synthetic indigo was facilitated by the discovery 

 of the catalytic acceleration of the oxidation of 

 naphthalene by mercuric sulphate, discovered 

 owing to the breakage of a thermometer bulb in 

 the reaction mixture. The production of dye 

 intermediates involves, more and more, the aid 

 of catalysis. Especially, however, in the large- 

 scale preparation of solvents will catalysis con- 

 tribute convincingly to success. Industrial alcohol 

 may be cited in illustration. Every method by 

 which this important solvent is produced is cata- 

 lytic. The ordinary process of fermentation and 

 distillation involves the participation of the living 

 catalysts, the enzymes and ferments. The pro- 

 duction of alcohol from potato and rice starch is 

 a combined process of hydrolysis and fermenta- 

 tion with the catalytic action of acids followed by 

 enzymes. Similarly, alcohol of the future will be 

 obtained by catalytic degradation of the cellulose 

 content of wood waste, or, synthetically, from 

 acetylene and ethylene, by processes of catalytic 

 hydration and hydrogenation. The potentialities 

 of alcohol as a fuel in the future must not be 

 forgotten, in view of the increasing consumption 

 and prospective exhaustion of oil-fuel reserves. 

 In the meantime these latter, as a result of more 

 rigid scientific control, are being more economi- 

 cally utilised. The "cracking" of oils to yield 

 the more volatile fractions usable in motor-engines 

 is a modern development, the catalytic features 

 of which have not, as yet, been completely 

 realised. 



From alcohol as starting-point, catalysis is 

 involved in the production of acetic acid and 

 acetone, the solvents largely required in the pre- 

 paration of aeroplane dopes and varnishes. From 

 methyl alcohol, a distillation product of wood, 

 catalytic oxidation or dehydrogenation in presence 

 of metallic copper yields formaldehyde, a power- 

 ful germicide and disinfectant, and itself the start- 

 ing-point in the manufacture of bakelite, the arti- 

 ficial vulcanite or amber, a polymerised product 

 formed under the influence of catalytic agents, 

 and increasingly produced for use in electrical 

 insulators and for fancy articles. The demand for 

 formaldehyde Is already so great that investiga- 

 tions are in progress with the object of production 

 from sources other than methyl alcohol. The 

 hydrocarbon methane has been suggested in this 

 connection. A process of fractional oxidation of 

 methane should yield formaldehyde. Alcohols and 

 organic acids of varied complexity may be largely 

 utilised in the production of synthetic essential 



NO. 2605, VOL. 104] 



oils and perfumes by processes of catalytic con- 

 densation. 



The catalogue is not exhaustive, but sufficient 

 has been said to show the paramount importance 

 of catalysis in modern chemical industry. It is 

 evident, therefore, that the modern curriculum of 

 theoretical chemistry should concern itself largely 

 with the scientific principles involved in catalytic 

 reactions. An extended experience with catalysis, 

 both pure and applied, has demonstrated that, 

 from a complete realisation of the theoretical 

 aspects of the problem, progress in the application 

 follows the more rapidly and the more certainly. 

 It is astonishing to note the facility with which 

 new progress is attained by the employment of 

 the scientific principles which have been acquired 

 in a totally different application of catalysis to 

 industrial progress. The records of certain of the 

 Government Departments of investigative work, 

 during the last few years, would be instructive in 

 this regard. The need, therefore, is urgent for a 

 well-trained force of young students, versed in the 

 fundamentals of this modern branch of chemistry, 

 and equipped to take their place in the further 

 developments which lie so close at hand. There 

 are manifold possibilities ahead — numerous pro- 

 cesses and agencies catalytic awaiting the facile 

 brain and hand of the investigator. 



Hugh S. Taylor. 



FROSTS AND AGRICULTURE I\ THE 

 UNITED STATES. 



THE United States Department of Agriculture 

 has recently issued a publication on " Frost 

 and the Growing Season." This consists of a 

 series of maps in colours and some diagrams 

 from which the probable date of the last frost in 

 spring and the earliest in autumn may be seen 

 at a glance. An article on a paper by Mr. W. G. 

 Reed on this subject appeared in the issue of 

 Nature for May 23, 1918, and the present pub- 

 lication is also by the same author. 



Frosts are dividec* into three classes: "light," 

 "heavy," and "killing." The first two terms apply 

 to the amount of the deposit in the form of hoar- 

 frost ; the last only is dealt with in the paper, 

 and is defined on an occasion on which the screen 

 temperature fell below 32° F. In a country like 

 the United States there is naturally great varia- 

 tion in the length of the period that is free from 

 frost ; not only is there variation in latitude from 

 Florida to the Canadian border, but there is also 

 much difference in the height above mean sea- 

 level. The local topography is also important, 

 for while, in general, frost is more prevalent at 

 the greater altitudes, yet locally a small elevation 

 will prevent a frost, and in enclosed valleys the 

 hill-sides and the hill-tops may be less subject to 

 frosts than the valley bottoms. 



Frost records are available from about four thou- 

 sand regular stations of the Weather Bureau, and 

 of these about six hundred have a twenty years' 

 record. The most noteworthy feature of the 



