ii 4 SCIENCE PROGRESS 



organic solvent of high boiling point, such as nitrobenzene or 

 xylene, the temperature being kept between o° and 15 . After 

 twenty-four hours the mixture is distilled ; the first runnings 

 consist of unchanged aldehyde and then follows ethyl acetate. 



The preparation of urea from ammonium carbonate has also 

 recently formed the subject of two patents brought out by the 

 Badische Anilin- und Soda-Fabrik (Eng. Pats. 1914, 23939 and 

 24 1 1 7). According to the latter ammonium carbonate is 

 treated in an autoclave and the product is then heated in a 

 vacuum at about 75 ° ; unchanged ammonium compounds distil 

 out as carbon dioxide and ammonia and recombine in the 

 cooled receiver, while urea and water remain behind in the 

 still. The water is removed by further distillation in vacuo. 



The estimation of urea by urease has again received atten- 

 tion in papers by van Slyke and Cullen (/. Biol. Chem. 191 6, 

 24, 1 1 7) and Ibanez {Anal. Fis.Quim. 1916,14,28); on the other 

 hand Mom (Chem. Weekblad, 1916, 13, 72) describes a method 

 involving the use of Urobacillus Pasteurii which converts 

 urea into ammonium carbonate which can be estimated 

 volumetrically. 



GEOLOGY. By G. W. Tyrrell, A.R.C.Sc, F.G.S., University, Glasgow. 

 General and Stratigraphical Geology. — The first volume of 

 the geological results of the Shackleton Antarctic Expedition 

 of 1907-9 is now to hand. As might be expected, more 

 than half the volume, which is written by Prof. T. W. E. 

 David and R. E. Priestley, deals with the manifold ice- 

 forms and ice-work of Antarctica. Many proofs are ad- 

 duced that the glaciation of the continent is now in a waning 

 phase. The Ross Barrier, for example, has shrunk vertically 

 about 1,000 feet, and horizontally at least 200 miles, since the 

 period of maximum glaciation. An instructive parallel is 

 drawn between the Ross Barrier and the ice sheet which filled 

 the North Sea during the Pleistocene glaciation. An ascent 

 of Mount Erebus has added much to knowledge of the vulcanism 

 of the Ross Sea area. Including the present, Erebus has had 

 no less than four distinct craters. The stratigraphical geology 

 of Victoria Land is dealt with at length. The succession in- 

 cludes Pre-Cambrian gneisses and limestones, a Cambrian 

 formation containing Archaeocyathinae, and sandstones re- 

 ferred to Gondwana sedimentation. The igneous rocks include 



