6:;S 



NA TURE 



[October 29, igo8 



Doxter developed ihe Dexler breed of cattle by cross- 

 ■li; the true Kerries on cattle of a beefy sort, pos- 

 :b!v Shorthorns? A\'as the cow called Ued Rpic 



liiili produced nearly 10,000 lb. of milk in a year 

 i true Kerrv? Is the cow figured on p. 380 as a 

 Dexter-Kerry really a Dexter-Kerry? Is the out- 

 come of the cross of Shorthorn bulls on Galloway 

 cows usually a blue-grey ? Did the monks of the 

 Middle Ages have the Cheviot breed of sheep about 

 the pasture-lands of the old monasteries? Did 

 Oeorge Washington have Bakewell ewes at Mount 

 \"eTnon, or is it onlv " said "? Do black-faced sheep 

 ■subsist largely on heather? 



The answers to some of these questions may be 

 in the affirmative, but they need support before being 

 accepted. 



There are two breeds of cattle peculiar to 

 America, viz. the polled Durhams and the polled 

 Herefords, about the origin of which one would like to 

 have definite information. In both these breeds 

 there are what are called " double standards " and 

 " single standards " : the " double standard " animals 

 being pure-bred hornless sports and their descendants, 

 and the " single standards," in the case of the Here- 

 ford, being animals " not eligible to record in the 

 American Hereford Record," and, in the case of the 

 Shorthorns, animals " got by the use of Shorthorn 

 bulls on the native muley cows." W'e never hear of 

 hornless sports among pure-bred Herefords or Short- 

 horns in Britain, and some information as to the 

 circumstances in which these occur in .America would 

 be not only interesting, but useful to students of 

 heredity. 



James ^^'lLSON. 



POWER GAS PRODI CTION. 

 Poii'cr Gas Producers, their Design ami Applicalion. 

 By Philip W. Robson. Pp. iv-l-247. (London : 

 E. .Arnold, 1908.) Price 10s. 6d. net. 



'"THE wonderful advance in the production of power 

 -*- made by the suction gas plant combined with 

 the gas engine gives great importance to any trust- 

 worthy literature on the subject, and the work on 

 power gas producers by Mr. P. \V. Robson is certainly 

 one which will be warmly welcomed, as it sets the 

 subject out in a clear and concise manner, and 

 indicates the theory of the various actions, as well as 

 the means by which the application is carried out. 



As the author very fairly admits, it is difficult for 

 one engaged in the manufacture of a particular class 

 of producer to treat thoroughly of the work of other 

 firms, with the result that perhaps full justice has not 

 been done in every case; but as a whole the book is 

 wonderfully free from error, although there are a few 

 points which might be amended. 



The statement made on p. 17 that anthracite and 

 gas coke have practically the same proportion of 

 volatile matter is a little loose, as with a good gas 

 coke one does not expect to find more than i per 

 cent., whilst the average in anthracite is about s pcr 

 cent, to 6 per cent. On p. 2g the reader is left to 

 infer that, inasmuch as a temperature of 900° C. to 

 NO. 2035, VOL. 78] 



1000° C. favours the formation of carbon monoxide 

 rather than the dioxide, i; is the best to emjilay, whilst 

 practical conditions undoubtedly dictate a lower 

 temperature in order to avoid the tendency to clinker 

 which is so often found with fuels that are not of 

 quite the best quality. Indeed, some of the largest 

 producer makers hold that a temperature between 

 800° C. and 900° C. is the best for practical work- 

 ing. 



In the conclusion to this chapter, aNo, the state- 

 ment that an excessive amount of steam lowers the 

 temperature all round and is generally against 

 efficiency, preventing the production of a good gas, 

 is of course modified by the fact that within a fairly 

 wide range increase of carbon dioxide almost in- 

 variably means a corresponding increase of hydrogen, 

 and if this were not so it is quite clear that such t 

 processes as the Mond would not be possible, whilst 

 the advantage of an excess of steam over th" 

 theoretical quantity is in reduction of clinker and 

 ensuring free combustion of that portion of the carbon 

 which otherwise remains in the ash. 



In chapter iii. the statement is made that the 

 regulation of the steam is unnecessary, and in pro- 

 ducers of the " National " type this may be the case, 

 as it would be very difficult indeed to regulate a water 

 feed which has to distribute over half a dozen places, 

 but with other forms of producer it is certain that if 

 a less saturation of the air is arranged for low loads 

 and is increased in an increasing ratio at full loads, a 

 more imiform temperature is maintained in the 

 generator. 



On p. 46 indicator diagrams are shown of the 

 National and Crossley engines as illustrating con- 

 clusively that the gas produced with excess of steam 

 could not have been of such high calorific value as 

 that evolved in the National type of producer, but the 

 author has evidently overlooked the fact that in the 

 trial here quoted the National engine was taking full 

 gas, whilst the Crossley engine .had the gas charge 

 throttled so as to keep within the limits of power of 

 the trial. 



It is stated on p. 71 that the temperature of the gas 

 entering the cooling or coke .scrubber should be 

 600° F., but this temperature would be with ordinary 

 plants far too high, and would be taken as showing 

 that in the form of vapouriser used the heat was not 

 properly extracted. 



The author mentions on p. 106 that some French 

 makers have introduced a chemical purifier containing 

 o.xide of iron for the purpose of eliminating 

 sulphuretted hydrogen from the gas, but surely it is 

 unnecessary to give credit for what has been done in 

 everv gas works for very many years. 



oil the last line but one of p. 84 " per hour " should 

 be inserted after " 7A gallons," whilst in the table 

 on p. 136 the higher value of the heat efficiency for 

 the whole run should be So per cent. Instead of S per 

 cent., and there is a misprint on the third line from 

 the bottom of p. 221. 



The portions of .Mr. Robson "s work which deal 

 with bituminous gas plants are not nearly so good 

 as those portions that have reference to the use of 

 anthracite and colve, whilst the chapters on work 



