January 2, 1899.] 



KNOWLEDGE. 



to those of doubt. The fundamental conception of morpho- 

 logical investigation of the cell leaves us wholly in the lurch 

 in the case of plasmodia. Neither cell membrane, nor 

 nucleus, nor other histological elements can be established 

 in this case by the most benevolent interpretation of the 

 facts, and, twist the cell theory as we may, it certainly 

 cannot be fitted to the naked flowing protoplasm of the 

 Myxomycetes." Nuclei, however, have since been found in 

 Plasmodia. 



The cell walla of ordinary plants are composed of a 

 peculiar substance known as cellulose, and within these 

 the protoplasm of the cell is contained, with all that may be 

 contained in the protoplasm — the nuclei, the chlorophyll, the 

 colouring, and the oily matter, &c. The cell is thus a highly 

 organized unit, and it is, moreover, capable of carrying on 

 most marvellous operations, physical and chemical. 



An organism which commences life Ln the simple form 

 of a piece of protoplasm, in many cases produces cell walls 

 and rests in these, and thus builds a home for itself in 

 which it lives and labours. But in the case of the 

 Myxomycetes this does not occur, or occurs only very 

 exceptionally, and all the actions which these organisms 

 perform, and all the beautiful forms which they assume, 

 are reached without ever formmgaceU wall or constituting 

 a true cell, except in the spore itself. In these actions and 

 in these forms we see the capacities of simple and naked 

 protoplasm. The extreme simplicity of the mechanism 

 seems to bring to the mind more powerfully the inherent 

 powers of the worker. 



[To be continued.) 



OZONE AND ITS USES. 



AMONG the many interesting bodies which the 

 researches of modern chemists have brought to 

 light, few are more remarkable than the substance 

 to which Schonbein gave the name " Ozone " in 

 the year 1840. Little studied, this useful form 

 of matter had been recognised for fifty years before 

 receiving its name, which, as every reader with an 

 elementary knowledge of Greek will know, is meant to 

 accentuate one of its chief properties, its peculiarly strong 

 smell. Ozone was originally thought to be an oxide of 

 hydrogen, having a composition represented by the symbol 

 H5O3, but when several chemists independently succeeded 

 in obtaining it by passing electric sparks through perfectly 

 dry oxygen this was seen to be impossible. Further 

 researches conclusively demonstrated that ozone was 

 nothing more than a condensed form of oxygen. 



Though ozone has never yet been obtained in a pure 

 state, chemists have a very satisfactory knowledge of its 

 properties. Its smell resembles that of weak chlorine. 

 When compressed, ozone has a blue colour, and is 

 eventually converted into an indigo-coloured liquid, which, 

 according to Troost, boils at — 119"". It is a strong 

 oxidiser ; that is to say, it readily decomposes into 

 ordinary oxygen, at the same time combining with suitable 

 substances which may be present. It has been used in 

 this way to bleach engravings discoloured by age, but 

 the method is not altogether satisfactory. The possible 

 applications of the strong oxidising powers of ozone are 

 very numerous, since, while being so energetic an oxidiser, 

 its action is also very simple. Unlike other substances 

 used by chemists to give up their oxygen, ozone leaves no 

 residue behind. It has consequently been suggested that 

 ozone should be used to bleach beeswax, starch or bones ; 

 in the manufacture of varnishes, and also to accelerate the 

 maturing of wines and spirits. Though considerably more 

 experience than is at present available will be necessary 



before these applications of ozone can be successfully 

 accomplished, there seems no reason why, after the effects 

 of successive additions of the gas, and the adjustment of 

 the proper amounts necessary in each particular case, have 

 been studied, ozone should not become a very important 

 commercial product. 



It must, however, be at once pointed out that these have 

 only recently become practicable possibilities. Until the 

 advent of the process which we shall presently describe, 

 ozone had been prepared on a small scale only, either by 

 the action of the silent electric discharge on air or oxygen, 

 by the electrolysis of dilute sulphuric acid, or by the slow 

 action of clean phosphorus on moist air ; but by none of 

 these methods can it be obtained in any quantity. Of 

 these three plans for obtaining ozone that of the electric 

 discharge is the one most commonly employed in the 

 laboratory, and the form of apparatus in most general use 

 is known as " Siemens' induction tube." This consists 

 of a sort of Leyden-jar, formed of a smooth metal tube 

 which fits into a wider tube coated with tinfoil on its outer 

 siu-face, leaving a narrow annular space between them. 

 Between the two tubes a stream of dry oxygen gas is passed, 

 which, when the inner and outer coatings are connected 

 with the terminal wires of an induction-coil, becomes 

 electrified by induction, and from ten to fifteen per cent, 

 of the oxygen is thus transformed into ozone. 



But though pieces of apparatus like that of Siemens prove 

 satisfactory enough in preparing small quantities of ozone 

 suitable for chemical research, they are quite inadequate 

 for the generation of quantities large enough to be used 

 commercially. Mr. Andreoli has recently patented a pro- 

 cess which, though fundamentally similar to the laboratory 

 plan of Siemens, is yet able to produce ozone at a market- 

 able price. The construction of this patent is based upon the 

 familiar tendency of an electric discharge to flow off a point, 

 and in the apparatus designed by Mr. Andreoli, serrated 

 grids of aluminium, each carrying seventeen thousand 

 seven hundred and sixty points, are used. These grids 

 form electrodes, and each one is placed opposite a sheet of 

 aluminium with a plate of glass between. The three things, 

 the grid, the glass, and the aluminium plate, are bound 

 together by suitable wooden clamps. Though the con- 

 struction of the apparatus would naturally lead one to 

 suppose that occasional large sparks would occur from the 

 metallic points, and so cause the imion of some of the 

 oxygen and nitrogen in the air which is acted upon, Mr. 

 Andreoli states that no such compound of nitrogen and 

 oxygen is formed. If this really is so, the production of 

 ozone is uninterfered with, but this point requires to be 

 more thoroughly investigated by chemists before a definite 

 statement can be made with reference to it. 



The applications of ozone seem likely to rapidly increase 

 in number. It has become very popular among sanitary 

 specialists as a means of purifying contaminated air. It 

 is employed medicinally for the cure of persons suffering 

 from fcetor of the breath, the inhalation of ozone causing 

 a complete disappearance of the unpleasant symptoms. 

 In the treatment of ulcers and wounds of all kinds it has 

 proved invaluable, for under the influence of ozone such 

 diseased parts readily become healthy, rapidly exhibiting 

 an active tendency to heal. It is becoming common to 

 ens'ire the sanitation of hospital wards by diluted ozone. 

 The organic germs are destroyed by the oxidising power of 

 the ozone, and consequently the bacteria of typhoid, cholera, 

 dysentery, small-pox, fevers, etc., are killed. 



In all those industries where oxidation plays an 

 important point, ozone is becoming more and more used. 

 Thus it has been employed for sterilizing foul casks and 

 vats ; for the rapid oxidation of drying oils ; for seasoning 



