7IO 



NATURE 



[January 27, 1921 



the retorts in return for a small extra capital expendi- 

 ture and the cost required to drive the fan on the 

 outlet boilers. The author points out in this connec- 

 tion what is so frequently ignored by the less 

 informed advocates of low-temperature carbonisation, 

 . that in the continuous vertical retort a really frac- 

 tional distillation can be attained. "The products of 

 distillation are driven away as made, and have to pass 

 through no higher temperature than that at which 

 they are evolved, whilst if water-gas is made at the 

 same time in the retort by steaming, this process 

 protects the hydrocarbons and gives a greater quantity 

 of a lighter quality tar." The weakness of gasworks 

 practice, from the author's point of view, is that the 

 coal has to be conveyed to the gasworks and the 

 coke removed from it. 



In dealing with coke-ovens it is argued that they 

 meet a definite but limited demand for a specific 

 article, namely, hard coke for blast-furnace work, and 

 that on this account the erection of coke-ovens for 

 supplying gas- and tar-oils to meet national needs is 

 not feasible. 



The author turns aside for a moment to indicate 

 the possibility of using much more coke-oven gas for 

 town supply, and points out that the chief difficulty 

 in the way at present is the variation in its quality. 

 That difficulty is not, however, insuperable. 



He expresses, too, a belief that gas will in the 

 future be used instead of coke in the smelting of iron- 

 ore, but it is possible that in coming to that con- 

 clusion the high output and efficiency of a modern 

 blast-furnace plant have not been taken sufficiently 

 into account. 



Sir Arthur does not regard gas-producers very 

 favourably, though he admits their power of giving a 

 large supply of heat-units in the form of gas at a low 

 cost. His main criticism is that the tar-oils recovered 

 are not valuable. "The condition in which they come 

 from the plant makes them difficult to work up, and, 

 according to the tar distillers, the final products do 

 not compare at all favourably in value with the final 

 products from other methods of destructive distillation 



of coal." In justice to the gas-producer it may be 

 pointed out, however, that most of the criticisms 

 under this head might be applied equally well to pro- 

 ducts of other processes of low-temperature distilla- 

 tion, and often mean simply that the tar is very 

 poor in aromatic constituents, different from gas- 

 works tar, and cannot be worked conveniently along 

 with it. 



In speaking of low-temperature carbonisation the 

 author makes the pertinent observation that its advan- 

 tages are too obvious. He goes on to indicate that 

 the difficulties it presents are very real, and, of course, 

 it cannot attain his ideal because so much of the fuel 

 is finally left in the solid form. 



The whole of these considerations and criticisms of 

 the shortcomings of different processes have been 

 leading up to a proposal of something different- — total 

 gasification in some form of plant which differs from 

 a gas-producer in that air is not used for gasification 

 of the fixed carbon, and, therefore, nitrogen in 

 quantity is not present in the gas. " The principle of 

 this process is the partial carbonisation of coal in a 

 vertical retort superimposed on a water-gas generator, 

 the retort being heated externally by means of the 

 products of combustion of the producer during the 

 blow period, and internally by the passing of the 

 water-gas made up through the charge in the retort." 



This comprehensive survev ends with the formula- 

 tion of an ideal system of manufacture to meet the 

 demands for liquid and gaseous fuels. It is to gasify 

 coal completely, preferably in one vessel, recovering 

 in a liquid form the maximum amount of volatiles in 

 the coal (working with any coal) and preserving the 

 resulting ammonia. It would be of the combined 

 vertical retort water-gas-producer type, with recupera- 

 tors, waste-heat boilers, and mechanical arrange- 

 ments making for labour-saving and for high thermal 

 and chemical efficiency. It is to the treatment in some 

 such plant as this that the author looks for increas- 

 ing our home-produced oil-fuel supplies, and no doubt 

 he is willing to take his share in the skilful design 

 and careful experimental work involved. 



Sheep Panics. 



A SHEEP panic on the night of December lo-ii, 

 in which the sheep broke their folds in twenty 

 parishes in an area extending some twenty miles in 

 the highest part of Cambridgeshire, has been attract- 

 ing attention. These panics have often occurred, for 

 sheep are notoriously timid and nervous animals. On 

 November 3, 1888 — an intensely dark night, with 

 occasional flashes of lightning — tens of thousands of 

 folded sheep jumped the hurdles and were found scat- 

 tered the next morning. Every large farm from Wal- 

 lingford to Twvford was affected, and those on the 

 hill country north of the Thames most so. Again, on 

 the night of December 4, 1893, another very remark- 

 able panic among sheep occurred in the northern and 

 middle parts of Oxfordshire, extending into adjoin- 

 ing parts of the counties of Warwick, Gloucester, 

 and Berks. 



Various causes for these panics have been sug- 

 gested, but only one reasonable explanation has been 

 satisfactorily adduced. The 1893 panic was, at the 

 time, fullv investigated by Mr. O. V. Aplin, who 

 published "in the Journal of the Royal Agricultural 

 Society the result of his inquiries and the conclusions 

 he drew from the extensive evidence collected. The 

 conclusion arrived at was that the cause of the panic 

 was simply thick darkness. Very few people, prob- 

 ably, have ever been out in a really dark night, and 



NO. 2674, VOL. 106] 



it is impossible for anyone who has not had this 

 experience to imagine what it is like and the sense 

 of helplessness it causes. That a thick darkness of 

 this kind was experienced in the early part of the 

 night of the recent panic (at a time agreeing with 

 that at which, so far as was known, the sheep stam- 

 peded) was proved by abundant evidence. One report 

 said that it was between 8 and 9 p.m. when such a 

 thick and heavy darkness came on that a man could 

 not see his own hand. Another witness wrote that 

 a little before 8 o'clock there w-as an extraordinary 

 black cloud travelling from north-west to south-east, 

 which appeared to be rolling along the ground. The 

 darkness lasted for thirty or forty minutes, and during 

 that time it was like being shut up in a dark room. 

 Later in the night — long after the panics — there were 

 several flashes of lightning. 



Mr. Aplin states that animals probably see per- 

 fectly well on ordinary dark nights, and we can 

 imagine a bewilderment coming over them when they 

 find themselves overtaken by a thick darkness \n 

 vihich they can see nothing. Folded sheep (and it 

 was the small folds that the sheep broke most) in 

 moving about would knock against their feeding- 

 trouglis and one another, and the first one that got a 

 fright from this and made a little rush would prob- 

 ably come into collision with one or two others, and 



