4i6 



NA TURE 



[September i, r 



deposited in this way. Thus wide sheets of boulder-clay 

 and the "end-moraines" of a great ice-sheet have had 

 the same origin — they consist of ground-moraine accumu- 

 lated under the thinner peripheral portions of the ice. 



According to the author there is no doubt that the 

 action of the ice favours the formation of rock-basins. 

 Should a depression or hollow occur underneath an ice- 

 sheet, and the ice be thicker in the hollow than over the 

 adjacent tracts, the hollow will tend to be progressively 

 excavated. He thinks, however, that the erosive work 

 of the ice will tend rather to the lengthening of the 

 hollow in the direction of glacial movement than to its 

 deepening. Wherever the ice is thickest there erosion 

 will be most pronounced, no matter what the form of the 

 land-surface may be. Thus rock-basins may be hollowed 

 out even in relatively flat land, as, for example, by a 

 glacier upon the low ground opposite the mouth of a 

 mountain valley. 



Such are a few of the many interesting points con- 

 nected with glacial action which are discussed by Dr. 

 Drygalski. He concludes his work by some very sug- 

 gestive remarks on the wonderful resemblances that 

 obtain between the old gneiss-formation and the "in- 

 land ice " — the oldest and the youngest Erstarrungs- 

 produkte of the earth's crust. When he had surveyed 

 the steep gneiss-walls of the fiords, with their folded, 

 contorted and confused bedding, their bands of crystal- 

 line schist, their veins and dykes, their fissures and 

 fractures, he was astonished to encounter the same 

 appearances in the " inland ice," and he follows the 

 analogy into minute details of structure. But enough 

 has been said to show that Dr. Drygalski's monograph 

 is of no ordinary interest to geologists. 



The chief object of the expedition being the study 

 of ice in general and of the movement of the " inland ice " 

 in particular, the. opportunities for biological investiga- 

 tion did not at first appear to be very promising to Dr. 

 Vanhoffen. But in this he was happily disappointed, 

 for he succeeded in bringing home much material for 

 study. His contribution to the work before us occupies 

 the greater portion of the second volume. In this he 

 does not confine himself to a mere description of his own 

 investigations and their results, but gives us an ex- 

 haustive account of the fauna and flora of Greenland, 

 including of course the life of the adjacent seas. For the 

 benefit of those who are not specialists he illustrates his 

 work with a number of beautiful coloured plates of some 

 of the crustaceans, pteropods and jelly-fish which swarm 

 in the waters of the far north. A copious bibliography 

 is appended — great pains, indeed, have been taken to 

 give a complete survey of the natural history of Green- 

 land. A more special and detailed account of his own 

 investigations is to appear in the Bibliotheca Zoologica 

 and Bibliotheca Botanica (Stuttgart). 



The concluding part of the second volume is devoted 

 to the discussion of the magnetic, meteorological, 

 astronomical and geodetic work of the expedition by 

 Drs. Stade, Drygalski, and Schumann. Dr. Stade 

 devotes a chapter to the fohn winds of West Greenland, 

 which have long puzzled navigators and excited the 

 superstitious fears of the Eskimo. Coming as these 

 warm winds generally do from the ice-covered land, 

 especially in the coldest time of the year, they seem 

 hard to account for. According to Dr. Stade they owe 

 their origin to depressions passing through Davis Strait 

 from south to north. The approach of a depression is 

 marked by strong to stormy winds from the south-east 

 or east, the temperature of the atmosphere suddenly 

 rising, while at the same time its relative humidity is 

 reduced. 



Altogether this most recent of Arctic expeditions has 

 been fruitful in results, and the Geographical Society 

 of Berlin must be congratulated on the great success 

 which has attended the enterprise. J AMES Geikie. 



NO. 1505, VOL. 58] 



THE PRODUCTION AND USES OF OZONE. 



npHOUGH it has been known for more than a century 

 -*• that air and oxygen acquire a peculiar odour when 

 exposed to the action of electric sparks, and though 

 Schonbein ascertained nearly half a century ago that this 

 odour is due to a distinct form of matter, now called 

 ozone, which is produced by the electrolysis of dilute 

 sulphuric acid, by the action of electric discharge in air, 

 and as a product of the slow oxidation of phosphorus, 

 chemists are still trying to learn the exact conditions of 

 the formation of this substance, and still investigating 

 some of its simplest reactions ; whilst inventors are 

 but beginning the work of making it useful to man. 



But if the wheels of science grind slowly, in the end 

 they grind true, and various facts now distinctly suggest 

 that ere long ozone will play a useful part in the service 

 of medicine, of surgery, and in the arts. 



Ozone has never yet been obtained as a gas in the 

 pure state, but from the properties of mixtures containing 

 it we cannot doubt that gaseous ozone would be blue 

 in colour, and condense at low temperatures to an 

 indigo-blue liquid, which explodes violently on contact 

 with olefiant gas. The ozone in mixtures, such as are 

 produced by the electrification of air or oxygen, is 

 very instable, being resolved into common oxygen with 

 explosive violence if suddenly compressed without pre- 

 vious cooling ; and even under atmospheric pressure it 

 cannot long be preserved except at rather low temper- 

 atures. This characteristic instability of ozone is at once 

 the cause of its most interesting properties and of 

 its possible usefulness. Molecules of common oxygen 

 contain but two atoms of the element, whilst the mole- 

 cules of ozone contain three such atoms, and it would 

 seem that the atoms hold together much less firmly in the 

 larger molecules than when they are united in pairs ; 

 consequently ozone acts as a powerful oxidiser, readily 

 giving up part of its oxygen to oxidisable substances, 

 whilst the rest returns to the ordinary form of the 

 element, except in certain cases when it is completely 

 absorbed. 



Now chemists have, it is true, plenty of powerful 

 oxidisers at their command, and many of them are in- 

 expensive ; but not even hydrogen peroxide, which can 

 now be obtained comparatively cheaply, is quite so 

 simple in its action as ozone, for this substance, which 

 consists, as we have seen, of oxygen and of oxygen 

 alone, when used as an oxidiser does not leave any 

 inconvenient residue, such as accompany the action of 

 many other oxidising agents. Hence a field for the em- 

 ployment of ozone may be found whenever a simple 

 oxidising agent is required. Thus, for example, it has 

 been suggested that it might conveniently be used for 

 bleaching beeswax, starch or bones, in the manufacture of 

 dSgras for leather makers, in preparing drying oils for 

 the manufacturers of varnishes, or again, according to 

 Wiedermann, to hasten the ageing of whiskey. 



There are, however, as might be expected, difficulties 

 to be surmounted. Sometimes, as in its action as a 

 bleaching agent, ozone is apt to act too slowly ; whilst 

 at others it is difficult to adjust the proper dose of the 

 oxidiser. Thus we are told that port wine treated 

 with ozone forms a deposit which quickly increases, 

 so that the wine soon puts on an appearance which, 

 under ordinary circumstances, it would only acquire 

 in the course of years. But, alas ! wine thus rapidly 

 ripened is apt to fade with corresponding rapidity, owing, 

 it is presumed, to the use of too much ozone, and hence, 

 in the absence of any obvious method of estimating the 

 proper dose, ozone does not yet recommend itself to wine 

 makers or wine merchants. It has occurred to the writer, 

 however, that it might possibly be made useful, even at 

 the present stage, in judging unripened wine, since its 

 use might enable the vintner to ascertain without delay 



