March io, 19 io] 



Na ture 



47 



In regard to material equipment, the autiior holds views 

 of a very advanced character. Necessity is not the mother 

 of invention ; knowledge and experiment are its parents. 

 This is clearly seen in the case of many industrial dis- 

 coveries ; high-speed cutting tools were not a necessity 

 which preceded, but an application which followed, the 

 discovery of the pro{>erties of tungsten-chromium-iron alloys ; 

 so, too, the use of titanium in arc lamps and of vanadium 

 in steel were sequels to the industrial preparation of these 

 metals, and not discoveries made by sheer force of necessity. 

 Much the same consideration applies to the equipment of 

 an industrial laboratory, where the most useful tools were 

 often acquired with no idea of the uses to which they 

 would ultimately be put. " Xo good tool lives long for a 

 single use alone. Many times we have questioned the 

 advisability of installing some new apparatus — a vacuum 

 furnace, a pair of metal rolls, some special galvanometer, 

 some microscope, a hydraulic press, a power hammer, a 

 steam digester, &c. Never, after it became a part of the 

 equipment, has it seemed possible to proceed without it. In 

 the single case of the electric vacuum furnace, for example, 

 our laboratory has made almost continual use of from three 

 to eight for the past five years. The laboratory, piped 

 several years ago with high vacuum and with electrolytic 

 hvdrogen, besides steam, air, water, and gas, will probably 

 never operate without them." 



Similar considerations apply to a library. A library con- 

 taining ten of the leading research journals of the world 

 may be said to have in each volume about 100,000 brain- 

 power hours, and it would be folly not to utilise a charged 

 storage-battery of this immense capacity when it'can so 

 readily be installed. 



SOME RECENT APPLICATIONS OF OZONE. 



A LTHOUGH ozone has now been definitely known for 

 -^~*- nearly, seventy years, its commercial production and 

 exploitation is one of the many bye-products that have 

 resulted from the modern development of electrical engineer- 

 ing. The " Ozonair " Company, of 96 Victoria Street, 

 Westminster, has taken advantage of these developments 

 to produce a series of compact and (in many cases) port- 

 able ozonisers which can be connected directly to the 

 ordinary lighting circuits and set in operation by means 

 of a couple of tumbler switches, one controlling a fan or 

 blower, and the other a coil or transformer for energising 

 the aluminium gauze in contact with which the ozone is 

 produced. The simplicity of these arrangements should 

 prove an important factor in securing the general utilisa- 

 tion of ozone in all those cases in which its usefulness 

 has been conclusively demonstrated. 



Most of the new designs are intended for the purifica- 

 tion of air, and in the case of large buildings their utility 

 and efficiency can scarcely be doubted. In a small room 

 or in close proximity to a generator, the presence of an 

 excess of ozone might well be disagreeable, as those who 

 have worked with it have good reason to know, but in 

 a crowded hall the atmosphere of a public meeting would 

 stand to gain enormously by the freshening and purifjing 

 effects of one or two well-placed ozpnisers. In cases such 

 as the above it is difficult, and in many buildings 

 impossible, during the winter to introduce enough air from 

 outside to prevent the atmosphere from becoming " stuffy," 

 but the most dangerous and unpleasant effects might well 

 be got rid of by means of ozone. 



This general idea has been worked out into a definite 

 and novel scheme of ventilation, which is acquiring con- 

 siderable popularity in Russia, where warmth and fresh- 

 ness have usually presented themselves as alternatives 

 rather than as compatible qualities, and in the tropics, 

 where the introduction of large volumes of air from the 

 outside is sufficient to destroy whatever remnants of cool- 

 ness may be retained by the use of verandahs and other 

 devices for excluding the glare of the sun. In each of 

 these^ widely differing circumstances the method used is 

 to withdraw air from the room, purify it by screening, 

 washing, and ozonising, cool or warm as the case may 

 be, and return it to the room with a sufficient admixture 

 ^' lutside air to keep the proportion of carbon dioxide 

 :n reasonable limits. In this way a great economy of 

 NO. 2106, VOL. 83] 



heating or cooling is achieved, whilst the wholesomeness 

 of the atmosphere is fully maintained. 



The sterilisation of air by means of ozone has found a 

 widespread application in brewing, where it replaces with 

 great advantage the cumbrous and only partially effective 

 systems of air-filtration that have been employed to protect 

 the wort during fermentation, cooling, refrigerating, and 

 bottling ; it is also of service in protecting the yeast from 

 contamination whilst it is "being drained off from the wort. 



An application of ozone of a more familiar type :s in 

 the bleaching of palm-oil for soap-making. This has 

 usually been effected by means of bichromate and muriatic 

 acid at a cost which may amount to as much as 305. per 

 ton. The bleaching of the oil by ozone is very effective, 

 even in the case of specially bad samples, and costs little 

 more than a tenth of this sum ; in addition, the dark 

 sediment that is thrown out during purification is much 

 smaller in bulk, and the waste of oil is therefore greatly 

 reduced. 



It is claimed that the ozonised air produced by the new 

 types of apparatus is entirely free from oxides of nitrogen, 

 a point of considerable importance in many of its com- 

 mercial applications. 



AMERICAN ECONOMIC ENTOMOLOGY. 



A CCORDING to the twenty-fifth report of the State 

 ■^ Entomologist on the noxious and beneficial insects 

 of Illinois, the scope of the work of the Entomological 

 Department of that State has been very largely increased 

 as the result of special legislative enactments, and the 

 present report is the first to be drawn up under the new 

 conditions. Its contents consist of three articles, one on 

 experiments to check the corn-root aphis, a second on the 

 habits of the corn-field ant (Lasius niger atnericanus), and 

 a third on the insects infesting clover and alfalfa. Since 

 all three have been already issued as Bulletins of the Agri- 

 cultural Experiment Station of Illinois University, they 

 need not be further noticed. 



The mites of the group Oribatoidea form the subject of 

 an article in vol. vii. of the Bulletin of the Illinois State 

 Laboratory of Natural History. These mites, which are not 

 much larger than the head of an average pin, are charac- 

 terised by their hard, chitinous integument, on account of 

 which they are commonfy spoken of as beetle-mites, 

 although they are not to be confounded with the mites 

 infesting coprophagous beetles. They are generally found 

 under decaying timber, beneath bark, under stones, in 

 moss or grass, or on the twigs of trees, and do not 

 appear to inflict any special damage on crops. In the 

 present article Mr. H. E. Ewing describes a number of 

 new species. 



In article 2 of vol. viii. of the same publication Mr. 

 J. D. Hood gives descriptions of new generic and specific 

 types of thrips of the group Thysanoptera from Illinois. 



Army-worms and cut-worms infesting sugar-cane in the 

 Hawaiian Islands form the subject of Bulletin No. 7 of 

 the Entomological Division' of the Experiment Station of 

 the Hawaiian Sugar-planters' Association, published at 

 Honolulu. Of the various species of " army-worms," the 

 widely spread Cirphis unipuncta is abundant in the islands, 

 but the larvae do not seem to assemble in the hordes which 

 have given rise to the name of the group. They inflict, 

 however, considerable damage on young sugar-cane, 

 although, fortunately, there is an interval between the 

 disappearance of one brood and the development of a 

 second, which affords time for the plants to recuoerate. 

 The numbers of the grass army-worm — the caterpillars of 

 the moth Spodoptera mauritia, a soecies indigenous to 

 Mauritius, western Africa, and the Oriental and .Austral- 

 asian regions — have been kept in check in Hawaii, where 

 they formerly did much damage, by the introduction of 

 myna birds from India. 



Since weevils are a group with which the economic 

 entomologist has many dealings, reference mav be made 

 here to a paper on North American Curculionidae, by Mr. 

 W. D. Price, published as No. 1708 of the Proceedings of 



i the U.S. National Museum. A number of new species are 



: named and described. 



