Jan. 22, 1880] 



NATURE 



273 



minimum by pure tin. A second series of alloys was then 

 prepared, the mixtures of the constituent metals being 

 made without reference to the chemical equivalents or 

 the atomic weights of the metals, but a constant difference 

 of 5 per cent, being maintained between each two alloys 

 in the series. An attempt was made to obtain the tem- 

 perature of pouring of this series by a well-known calori- 

 metric method, but the results, of course, only profess to 

 be approximate and relative, as the specific heats of the 

 alloys are deduced from the mean specific heats of the 

 constituents, and are assumed to be the same in the 

 liquid as in the solid state. The numbers given, however, 

 differ widely from those usually accepted, the " tempera- 

 ture of casting" of copper, for instance, being given as 

 1,909° C, while M. Violle {Comptcs Rendus, t. lxxxix. 

 p. 702) considers its melting point to be 1,054° C. It is 

 probable therefore that the metals were poured at tempe- 

 ratures considerably above their points of fusion. The tests 

 by transverse stress were repeated on this series of alloys 

 and the results led the committee to conclude that they 

 " do not seem to corroborate the theory given by some 

 writers, that peculiar properties are possessed by alloys 

 which are compounded of simple multiples of their atomic 

 •weights or chemical equivalents. ... It does appear 

 that a certain percentage composition gives a maximum 

 strength, and another certain percentage a minimum, but 

 neither of these compositions is represented by simple 

 multiples of the atomic weights. Besides, there appears 

 to be a perfectly regular law of decrease from the maxi- 

 mum to the minimum strength which does not seem to 

 have any relation to the atomic proportions, but only to 

 the percentage composition." 



These conclusions are of the utmost interest and are 

 certainly somewhat startling ; it may be well to point out 

 therefore incidentally that, since the report was pub- 

 lished, it has been shown in this country that in the curves 

 representing the induction-balance effect and the electrical 

 resistance of the tin-copper alloys two critical points are 

 occupied by alloys in which the constituent metals are 

 combined in the very definite atomic proportions repre- 

 sented by the formulae SnCu 3 and SnCu 4 respectively. 



In summing up the results, the committee point out 

 that the curves of resistance to tensile and torsional stress 

 agree very closely, the curve of transverse resistance being 

 similar, but the compression-curve is very unlike either of 

 the others, the maximum compressive resistance being 

 " reached by one of the brittle alloys, the tensile strength 

 of which is not far from the minimum. It appears, there- 

 fore, that the tensile and compressive strengths of the 

 alloys are in no way related to each other ; that the 

 torsional strength is closely proportional to the tensile 

 strength, and that the transverse strength may depend, in 

 some degree, upon the compressive strength as is indi- 

 cated by the approach of some portions of the transverse 

 curve to the compression curve, but is much more nearly 

 related to the tensile strength, as is shown by the general 

 correspondence of the curve of transverse with that of 

 tensile strength. From the curves of transverse, tensile, 

 and torsional strengths it is seen that the strengths of the 

 alloys at the copper end of the series increase rapidly with 

 the addition of tin, until about 4 per cent, of tin is reached. 



The specific gravities obtained by the committee are 

 corrected for temperature and are reduced to the standard 



of water of maximum density. The results obtained by 

 Mallet, Alfred Riche, and other experimenters are plotted 

 side by side, but it is much to be regretted that those of 

 the committee are only represented by a mean curve 

 which at first sight is rather misleading. 



The appendix to the volume contains several reprints 

 of important monographs on alloys. There is also a 

 valuable bibliography which might, however, have been 

 more complete, and should surely have contained refer- 

 ences to such important work as Mallet's on the density 

 of metals in the fluid state, to some of the metallurgical 

 researches of Eliot and Storer, and to Knox and Mac- 

 gregor's on the thermo-electric properties of certain alloys. 



Viewing the results as a whole there can be no question 

 that metallurgists have reason to be grateful for the col- 

 lection of facts which have been so laboriously gathered, 

 and we trust it will not seem ungracious to express the 

 wish that the work had been undertaken in this country. 

 W. Chandler Roberts 



OUR BOOK SHELF 



The Spiders of Dorset, with an Appendix containing 

 Short Descriptions of those British Species not yet 

 found in Dorsetshire. By the Rev. O. Pickard- 

 Cambridge, M.A., C.M.Z.S., &c. From the Proceed- 

 ings of the Dorset Natural History and Antiquarian 

 Field Club. Vol. i., pp. 1-235, with Three Plates, Svo. 

 (Sherborne: L. H. Ruegg, 1879.) 

 Although this book has been in our hands for several 

 months, we have hitherto refrained from noticing it, 

 hoping the second volume might come to hand, and thus 

 have enabled us to give a more complete analysis. In 

 the meantime the importance of the work deserves at 

 least a preliminary examination. 



Mr. Pickard- Cambridge's reputation as an arachnologist 

 is a sufficient guarantee that any work written by him 

 will be carefully executed. He states that his first idea 

 was simply to give a list of the species found in the 

 county in which he has so long been resident. Subse- 

 quently it was determined that the work should be mono- 

 graphic so far as the Dorsetshire species are concerned. 

 It was then found that the species of the county included 

 over two-thirds of those that occur in Britain, and it was 

 decided to give diagnostic characters of the remainder, 

 thus rendering the woik a Handbook of British Spiders. 

 There was urgent need for such a work. With the 

 exception of a semi-popular outline sketch there has been 

 nothing claiming to be monographic since the now vener- 

 able Air. Blackwall published his magnificent Ray Society 

 Monograph in 186063. This work noticed 304 species. 

 Mr. Cambridge states that 510 are now known to him as 

 British, and that 358 of these have been found in Dorset- 

 shire. Considerable discrepancy exists in the nomen- 

 clature used as compared with that of Mr. Blackwall. This 

 has mainly resulted from the well-known labours of Dr. 

 Thorell, who, in his "Synonyms of European Spiders" 

 (notable as a work in the English language published in 

 Sweden), was the first to bring about tolerable uniformity 

 in this respect. But very little inconvenience arises 

 therefrom. Mr. Cambridge's handbook cannot supersede 

 Mr. Blackwall' s work with its magnificent coloured plates. 

 Both must be in the hands of all students of Arancidea; 

 the former elucidates and supplements the latter. 



Mr. Cambridge commences with a copious "Introduc- 

 tion" of forty-two pages, written in a pleasing and popular 

 style, so far as is compatible with a due explanation 

 of the anatomy, &c, and very readable to all so far as 

 his general remarks on the habits, means of capture, 

 preservation, &c, are concerned. Some of his remarks 



