56o 



NA TURE 



\Oct. 14, 1880 



liquid the pressure must be ahm'e a certain point," and goes on 

 to describe some experiments with ice, implying that ice is in 

 this respect a typical substance. Now our text-books speak of 

 the behaviour of water in freezing and melting as exceptional. 

 For instance, Prof. Balfour Stewart says ("Heat," p. 89) : "If 

 a substance expands in congelation, its melting-point is lowered 

 by pressure, but if a substance contracts in congelation, it^ 

 melting-point is rai-ed by pressure." And (p. 91) : "Bunsen 

 found that the melting-points of paraffin and spermaceti, both 

 of which contract when freezing, were raised by the application 

 of pressure." „ . , 



Do the new results tend to overthrow the generally received 

 opinions on the subject? oris there some way of reconciling 

 these seeming contradictions ? 



I have more interest in these matters than knowledge of them, 

 and must apologise if I am asking a question which I ought to 

 have been able to answer. C. A. M. 



October 2 



Mr. Haddon's Marine-Zoology Class 



Owing to misconceptions which have arisen from the notice 

 in Nature, vol. xxii. p. 517, relative to my marinezooloiry 

 class, I should like to state that this class was formed solely for 

 the purpose of the practical study of marine zoology, and without 

 any idea of founding a zoological station. I would also Uke to 

 take this opportunity of acknowledging my great indebtedness 

 to Prof. Dohrn's magnificent institution at Naples. 



Zoological Museum, Cambridge Alfred C. H addon 



Landslips 



I READ with great interest the article on landslips in Nature, 

 vol. xxii. p. 505. It is no doubt familiar to many that the salt 

 districts of Cheshire, in the neighbourhoods of Northwich and 

 Winsford, are subject to landslips of a peculiar kind. The beds 

 of rock salt occupying the posi: ion of the Triassic salt lakes are 

 the centre of an extensive unr'erground drainage. The fresh 

 water on reaching the salt proceeds to dissolve it and becomes 

 brine. This brine is pu 1 ped up and manufactured into white 

 salt. As the fresh water keeps constantly dissolving and eating 

 awny the solid salt, the superincumbent earths keep sinking, 

 and on the surface deep furrows, like the dried beds of rivers, 

 mark the course of the underground waters. At times enormous 

 masses of earth sink bodily, leaving cavities of a funnel shape. 

 A short time since a mass of at least 60,000 tons of earth 

 suddenly dis:-,ppeared. When these subsidences are near rivers 

 they become filled with water, and large lakes over 100 acres 

 in extent have been formed. Although houses are not over- 

 whelmed they are very frequently destroyed, and this destruction 

 of property is so serious that the sufferers are now about to 

 appeal to Parliament for assistance. 



The district of the salt manufacture presents phenomena both 

 curious and interesiing, and is well worth visiting. A fort- 

 night ago the whole of the water in one of these subsidences of 

 over five acres in extent disappeared, leaving a chasm or abyss 

 in many places forty or fifty fett deep. The action of water on 

 soluble rocks can be seen here in great perfection. 



Brookfield House, Northwich Thos. Ward 



LIQUEFACTION OF OZONE 



AT a recent meeting of the French Academy, MM. 

 Hautefeuille and Chappuis announced that they had 

 liquefied ozone. These chemists have been able to 

 ozonise oxygen to a greater extent than has hitherto 

 been done, by passing the silent discharge through the 

 oxygen at a low temperature. The tube containing 

 oxygen was immersed in liquid methylic chloride, which 

 boils at - 23°. After being submitted to the electric 

 discharge for fifteen minutes at this temperature, the 

 oxygen was conducted into the capillary tube of a 

 Cailletet's apparatus, tlje temperature of which was 

 maintained at - 1'^. • , 



After a few strokes of the pump the ' gas in the tube 

 appeared azure blue ; as pressure increased the depth of 

 colour likewise increased, until under a pressure of several 



atmospheres the ozonised oxygen appeared dark indigo 

 blue. The pressure was increased to ninety-five atmo- 

 spheres, and was then suddenly removed, whereupon a 

 mist, indicating liquefaction, appeared in the capillary 

 tube. 



The stability of a mixture of oxygen and ozone rich in 

 ozone appears to be chiefly dependent on the tempera- 

 ture. If such a mixture be rapidly compressed at ordi- 

 nary temperatures, a considerable amount of heat is 

 evolved and the gas explodes. 



Ozone, say MM. Hautefeuille and Chappuis, is therefore 

 to be placed in the category of explosive gases. 



Berthelot has shown that the transformation of oxygen 

 into ozone is attended with absorption of heat : the 

 stability of products of endothermic reactions is as a 

 rule increased by decreasing temperature. 



Ozone is much more easily liquefied than oxygen ; the 

 latter must be compressed under 300 atmospheres at 

 about the temperature of -29° before sudden removal 

 of pressure succeeds in producing liquefaction. 



We have thus the existence through a large range of 

 temperature and pressure of two allotropic forms of the 

 same element ; each with distinctly marked chemical 

 and physical properties. We know that the molecule of 

 oxygen has a simpler structure than that of ozone ; the 

 substance of simpler molecular structure is capable of 

 existing through a much more extended range of tem- 

 perature and pressure than that of more complex struc- 

 ture. Under special physical conditions it seems possible 

 that new allotropic modifications of various elements 

 might be produced. 



The marked differences in colour, and in temperature 

 of liquefaction, between oxygen and ozone, furnish 

 another illustration of the close connection which exists 

 between the " chemical structure" and physical properties 

 of substances; a different "linking," even of similar 

 atoms, being evidently associated with distinctly different 

 physical properties. 



j\IM. Hautefeuille and Chappuis will doubtless soon be 

 able to furnish more details of the properties of this 

 most interesting substance, liquid ozone. M. M. P. M. 



T 



THE UNIVERSITY OF NEW ZEALAND 

 HE University of New Zealand, with which, since 

 1874, the University of Otago has been affiliated, 

 has, we are glad to find, adopted a quite modern schedule 

 of subjects for its degree of B.A. 



The subjects of examination for the B.A. degree are :— 

 I. Greek Language and Literature. 2. Latin Language 

 and Literature. 3. English Language and Literature. 4. 

 Modern Languages and Literature. 5. General History 

 and Political Economy. 6. Jurisprudence and Constitu- 

 tional History. 7. Mathematics. S. Physical Science, 

 any two of the following branches : (<«) Sound and Light, 

 {U) Heat and Radiant Heat, {c) Electricity and Magnetism, 

 \ii) Astronomy and IMeteorology. 9. Chemistry. 10. 

 Natural Science, any one of the following branches : (a) 

 Geology and Mineralogy, {b) Zoology, (c) Anatomy and 

 Physiology, {d) Botany. 11. Mental Science. No candi- 

 date shall be approved by the examiners unless he show a 

 competent knowledge of at least five of the above subjects 

 of examination, of which two must be Latin and Mathe- 

 matics. The examination may be passed in two sections. 

 Either two or three subjects of examination, one of 

 which must be either Latin or mathematics, shall con- 

 stitute the first section, which may be taken at the end of 

 the second or any subsequent year, and the remaining 

 subjects shall constitute the second section, which may be 

 taken at the end of the third or any subsequent year; 

 or at the option of the candidate, all the subjects may be 

 taken together at the end of the third or any subsequent 

 year. , , 



In this curriculum the physical and natural sciences 



