NA TURE 



{Dec. 23, 1886 



rocks at the base of Mount Boijong, pronounced by Dr. von 

 Lendenfeld to be undoubted moraines (at an elevation of 1000 

 feet above sea-level). I may remark that these masses are too 

 extensive and distant from the steep spurs of Mount Bogong to 

 be considered as talus : besides which they show evidences of 

 translocation. 



I do not purpose entering into a description of further evidences 

 discovered by myself in the Mitta Mitta Valley, at Lake Omeo, 

 or Benambia Creek, &c., in the present paper. There will in 

 due course be communicated a second article on the evidences of 

 glaciation in the Australian Alps, together with a reply to later 

 criticisms. I merely desire to show that the evidences discovered 

 on Mount Kosciusko by Dr. von Lendenfeld are by no means 

 isolated, and that the highest mountain in Victoria, Mount 

 Bogong, presents features which confirm the evidences of glacia- 

 tion elsewhere, and that there is no a priori impossibility of the 

 area of glaciation being more extensive than has been assumed. 

 In conclusion, I would add that taking into consideration the 

 facts supplied to us by the examination of the ancient flora and 

 fauna of Australia as contained in the writings of Prof. Tate, of 

 South Australia, and of Mr. Wilkinson, F.G.S., of New South 

 Wales, and the geological evidences of glaciation over wide- 

 spread areas daily accumulating, it is difficult indeed to resist the 

 conviction that Southern. Australia, as well as South America 

 and Southern Africa, and indeed New Zealand, all participated in 

 a period of refrigeration, culminating in an ice-clad region during 

 later Pliocene or Pleistocene times, notwithstanding that many 

 difficulties suggest themselves in endeavouring to work out the 

 problem from mere localised observations. 



SORGHUM SUGAR 

 C OME months ago considerable interest was excited by a report 

 by Mr. Victor Drummond on the production of sugar from 

 sorghum and maize. The report was sent from the Colonial 

 Office to Mr. Thiselton Dyer, with a request that he would state 

 his opinion on the questions raised by Mr. Drummond. For 

 several years the importance of the subject had been recognised 

 at Kew ; and in his reply, dated August 10, 1886, Mr. Thiselton 

 Dyer expressed his belief that if sugar could be produced at a 

 cheap rate from sorghum and maize it would entirely take the 

 place of cane and beet sugar, the geographical range of sorghum 

 being far more extensive than that of the sugar-cane proper or of 

 the beet. At the same time he drew attention to the fact that 

 the results summarised Ijy Mr. Drummond had been for the inost 

 part derived from laboratory experiments only, and that the 

 question whether the new industry was likely to prosper could 

 not be determined until those results had been tested over wide 

 areas. He also pointed out that some statements in Mr. 

 Drummond's report were at variance with well-known facts in 

 vegetable physiology. Mr. Thiselton Dyer therefore advised 

 that e.xact information as to the position of the sorghum- and 

 maize-sugar industry in the United States should be obtained 

 through the Foreign Office. 



In accordance with this advice, copies of Mr. Drummond's 

 report and Mr. Thiselton Dyer's letter were sent to Sir L. West. 

 By him the matter was put into the hands of Mr. C. Hardinge ; 

 and now Mr. Hardinge's report has been published in the series 

 of Foreign Office "Reports on Subjects of General and Com- 

 mercial Interest." The sorghum-sugar industry has hitherto 

 been conducted on a small scale. In 1884 it was carried on at 

 eight factories, which produced i,crao,ooolbs. in all. Tlie com- 

 parative insignificance of this result will be seen when it is stated 

 th.it in 1S85 the quantity of cane-sugar consumed in the United 

 States was 1,170,000 tons. In most cases it was found that the 

 cost of extracting sugar from sorghum exceeded receipts, and at 

 the present time the industry is prosecuted at only two factories 

 — that of the Rio Grande Company and that of the Franklin 

 Sugar Company, whose works have been removed from Ottawa 

 to Fort Scott. 



Dr. Wiley, by whom the subject has been thoroughly investi- 

 gated, attributes the failure of the industry, so far, chiefly to the 

 following causes : — 



(I) The difficulties inherent in the plant have been constantly 

 under-valued. By taking the mean of several seasons as a basis 

 of computation, it can now be said that the juices of sorghum, 

 as they come from the mill, do not contain over 10 per cent, of 

 sucrose, while the percentage of other solids in solution is at 

 least 4, thus rendering the working of such a juice one of 

 extreme difficulty. 



(2) The chemistry of the process is at present hardly known, 

 and great development is necessary in this direction. 



(3) The area of land where the climate and soil are best 

 adapted for the cultivation of sorghum is not nearly so extensive 

 as was at first imagined, and investigation should be made in 

 order to discover in which localities the necessary conditions are 

 most favourable. 



(4) Commercial depression and the consequent low prices have 

 aff'ected this industry, and caused failure and losses in cases where 

 all other conditions were favourable. 



(5) Lastly, the mechanical treatment of the juice is very im- 

 perfect, the machinery used in the mills being quite inefficient 

 for the purposes intended. 



In order that the last-mentioned defect might be corrected, the 

 Commissioner of Agriculture decided that experiments for the 

 application of the process of diffusion on a practical scale should 

 be carried on with the best machinery possible, and the direction 

 of the experiments was intrusted to Dr. Wiley. He erected the 

 battery and necessary buildings in connection with the works 

 of the Franklin Sugar Company at Ottawa, Kansas, and the 

 first trial of the process of diffusion was made on October 8, 

 1885. The general results of the experiments of 1885 show 

 that :— 



(1) By the process of diffusion 98 per cent, of the sugar in the 

 cane was extracted, and the yield was fully double that obtained 

 in the ordinary way. 



(2) The difficulties to be overcome in the application of diffu- 

 sion are purely mechanical, and by enlarging the diffusion-cells 

 to a capacity of 130 cubic feet, and by making a few changes in 

 the apparatus, it would be possible to work 120 tons per diem. 



(3) The process of carbonatation for the purification of the 

 juice is the only method which will give a limpid juice with a 

 minimum of waste and a maximum of purity. 



(4) By a proper combination of diffusion and carbonatation, 

 95 per cent, of the sugar in the cane can be placed on the market, 

 either as dry sugar or molasses. 



When his experiments were ended, Dr. Wiley was instructed 

 by the Commissioner of Agriculture to proceed to Europe for 

 the purpose of inspecting and purchasing such forms of machinery 

 as might appear most useful, also to gain such information as 

 might secure the greatest success in this work ; and Mr. Hardinge 

 reports that much useful information, chiefly of a mechanical 

 nature, was obtained by Dr. Wiley during the course of his 

 visits to several of the most important sugar factories in France, 

 Germany, and Spain. 



During the season of 1 886 further experiments have been carried 

 on at Fort Scott, under the direction of the Department of Agri- 

 culture, and the results have not proved to be as satisfactory as 

 was anticiijated. 



ON THE CUTTING OF POLARISING PRISMS ^ 

 "T^HE author showed the manner of cutting two new polar- 

 ising prisms, designed by Ahrens and by himself, and 

 described and figured in the Phil. Mag. for June 1886. The 

 Ahrens polariser is a rectangular parallelopipedon of calc-spar 

 having square end-faces, and having its long sides in the propor- 

 tion of about I '6 : I relatively to the short sides. The square 

 end-faces are principal planes of section of the crystal. Two 

 oblique sections are cut in the prism, being carried through the 

 top and bottom edges of one end-face, and meeting in the hori- 

 zontal middle line of the others. The dihedral angle between 

 these planes of section is about 32°. The faces are polished 

 and reunited with Canada balsam in the usual way. The ad- 

 vantages claimed for the new prism are : (i) decrease in length, 

 (2) increase in angular aperture, (3) saving of light consequent 

 on non-obliquity of end-faces, (4) minimum of distortion, (5) 

 less spar required than in Hartnack, Glan, or Thompson prisms 

 of same section. Against this are the slight disadvantages of 

 (l) the line of section across end-face, and (2) the use of more 

 spar than a Nicol of equal section. But Mr. Ahrens has 

 recently added a thin covering-glass at the end-face crossed by 

 the line of section, thereby making this line almost impercept- 

 ible ; and he has also succeeded in finding a new method of 

 cutting the prism in which there is extremely little waste of spar. 

 The other prism designed by the author is a simple modification 

 of the Nicol, giving a wider angle of field. A wedge is cut off 



' Abstract of a Paper read at the Birmingham meeting, i336, of the British 

 Association, by Prof Silvanus P. Thompson. 



