568 



SCIENTIFIC NEV\^S. 



[June 15, lE 



together with an account of the lithological characters 

 and economic products of the stratified rocks, rather 

 than giving a knowledge of the elements and principles 

 of the science as a whole. 



At the commencement we have a woodcut of the 

 geologist cheerfully tramping along a road, with his 

 hammer and specimen bag over his shoulder, his pipe 

 between his teeth, and his dog bounding merrily at his 

 heels, and for a finis the same gentleman is depicted 

 seated at a desk completing the record of his labours, 

 attenuated it is true, but evidently joyful ; the doj, alas ! 

 is dead, but we confess we were neither overcome like 

 the dog, nor overjoj'ed like his master at coming 'to the 

 end of the book, as the only point we have to complain 

 about is the insertion of sundry woodcuts, which appear 

 rather out of place in a serious book of reference. 



Not the least useful part of the book is the account of 

 the economic products inserted at the end of the descrip- 

 tions of the various strata, including analyses of many of 

 the principal rocks, mineral waters, etc. In the account 

 of the economic products of the coal measures, there is a 

 curious statement of the products of the distillation of 

 lob tons of cannel coal, attributed to Sir H. E. Roscoe, as 

 follows : — Gas, 10,000 c. ff., or 22 tons; coke, about 60 

 tons ; ammonia liquor, 95 tons ; tar, 8| tons. Consider- 

 ing that the best cannel coal yields from 13,000 to 

 14,000 c. ft. per ton, the first item should surely be 

 1,300,000 or 1,400,000 ? 



The minute local variations of strata and general in- 

 formation thereon contained in the book, are very 

 accurately set forth, so far as we can check them from 

 personal acquaintance with many of the districts des- 

 cribed ; and the large coloured geological map of England 

 and Wales, is a most useful adjunct to a work of this kind. 



We wonder whether geologists will ever agree to a 

 universal system of colouring for these geological maps ; 

 at present the choice of colours to represent various 

 strata seems purely arbitrary, and is not a little con- 

 fusing. In an appendix we have a useful synopsis of 

 the animal kingdom, with especial reference to the fossil 

 forms, by E. T. Newton, F.G.S., F.Z.S. 



Ah Elementary Text-Book of Practical Metallurgy. By 

 Alfred Roland Gower, late Demonstrator in the 

 School of Metallurgy at the Birmingham and Mid- 

 land Institute. London : Chapman and Hall. 

 The want of a book which deals simply, systemati- 

 cally and judiciously with the subject of Practical Metal- 

 lurgy has long been felt. The existing text-books are, 

 for the most part, too large, or deal too exclusively with 

 assay ,methods. The publication of Mr. Gower's little 

 volume may therefore be hailed with satisfaction, as an 

 attempt to satisfy this recognised need. Unfortunatelj', 

 perhaps, it bears too plainly the brand of " South Ken- 

 sington ; " it being confessedly written for the elementary 

 students in the classes of the Science and Art Depart- 

 ment, the author was of course bound to follow the 

 stereotyped syllabus of that body, with the result that 

 his work is rather suggestive of the cramming which is 

 the bane of modern educational systems. The book is 

 divided into two parts, the first of which deals with the 

 matter required for the elementary stage, the second 

 with that for the advanced stage of the May Examina- 

 tions ; and as these requirements overlap, there is neces- 

 sarily in some places a little repetition. As far as it 

 goes the work is lairly complete; each of the subjects 

 laid down by the Kensington authorities is dealt with 

 carefully, and the various reactions are given at length 



with the accompanying calculations of quantities, and in 

 most cases a brief explanation 01 principles. The only 

 omissions of any consequence that we have observed 

 are : the chlorination and precipitation of gold ores ; 

 and the details of furnace manipulation, upon which the 

 sucess of an experiment so largely depends. 



The author rightly insists on the advantages of a 

 previous knowledge of chemistry ; but he has pre- 

 supposed a higher knowledge than is justified by our 

 experience of the men for whom he writes. He 

 frequently introduces terms which can be understood 

 only by one who has worked for some time in a chemical 

 laboratory; moreover the details of manipulation are 

 not adequately explained for a beginner. Again, at the 

 end of the book, among a group of useful appendices, we 

 find one which gives indiscriminately the specific gravi- 

 ties of gases as referred to hydrogen, and of solids as 

 compared with water, without any note to show which 

 of the elements is gaseous, which solid ; and another 

 which summarises in a series of equations without com- 

 ment, the principal reactions of the metals. Most of 

 the latter {e.g., Pb-rO = PbO) are entirely unneeded by 

 the chemist, whilst many would be utterly bewildering, if 

 not greatly misleading, to the tyro. 



We fear, indeed, that the plentiful use of equations 

 throughout the book (a fault on the right side, we admit) 

 may tend to leave an impression that the reactions at 

 high temperatures are far more definite, and less de- 

 pendent on the variations in general conditions, than is 

 actually the case. The author has adopted the usual 

 chemical notation, but we are at a loss to understand 

 why tartar should appear on page 3 as ToHoKo. Nor 

 can we clearly see why two equations are necessary to 

 explain the precipitation of barium suphate from the 

 chloride by a neutral sulphate — even if we admit the 

 correctness of the first equation : — 



KNaSO, 4- 2HCI = KCl + NaCl -t- H,SO, 

 H30, -f BaCL = BaSO, -f 2HCI. 

 Again, the electro-chemical equivalents of certain 

 elements (e.g., lead = 51-4, iron =14) are not those 

 usually ascribed to them. No allowance is made for the 

 possible loss of zinc in making brasses of standard com- 

 position. Omitting these and a few other slips, as for 

 example on p. 20, the occurrence of 140 for 150 as the 

 molecular weight of SnS, and the resulting errors in calcu- 

 lation, the book has evidently been carefully prepared and 

 revised. It is satirfactorily tree from misprints, although it 

 is somewhat unfortunate that the few which have crept 

 in occur in critical places; thus in the only example of 

 the method of calculating formulas from percentage com- 

 position, As-Fe,j is found instead of As-Fe,3. 



On the whole we commend the volume to those who 

 intend entering for the May Examination in Practical 

 Metallurgy, as a guide which will probably accom- 

 plish all that it professes to do-— to assist the candidate 

 to secure a " pass." 



A Plea for the Sparrows. — An almost unprecedented 

 attack of maggot has taken place in the Kentish fruit 

 plantations, and nut and apple crops have been, in many 

 instances, grievously damaged, if not destroyed. Planters 

 are making vigorous efforts to fight the pest, but the 

 grubs are so numerous that hitherto they have defeated 

 all attempts to get rid of them. The increase of insects 

 is said by the farmers to be due to the scarcity of spar- 

 rows, owing to the wholesale slaughter of the birds 

 which has been carried on in the district. 



