December 2, 1909] 



NATURE 



In the first chapters we have a brief but accurate 

 summary of the history of gold from the earliest 

 times, followed by an account of the properties of the 

 metal and its compounds of special value to the 

 metallurgist. The important subject, the alloys of 

 gold, is treated at greater length in the fourth 

 chapter, which is one of the most valuable parts of 

 the book, and contains an account of these alloys, 

 brief, it is true, but no essential points have been 

 overlooked. The attention of the metallurgical 

 student is especially called to this chapter, as it forms 

 a comprehensive introduction, such as is not found 

 elsewhere, to the detailed study of these interesting 

 mixtures of gold with other metals. The constitution 

 of these alloys, according to modern views, as 

 deduced from freezing-point curves and micro- 

 structure, is ably and clearly explained. In the subse- 

 quent chapters dealing with gold, the occurrence of the 

 metal in nature and the methods of extracting it from 

 ores are dealt with. Commencing with the simplest 

 and most primitive method of extraction, that of 

 simple " washing " practised from the earliest times 

 and culminating in the modern system of "dredging," 

 the various processes of amalgamation are passed in 

 review, and, finally, the so-called "wet" processes 

 are considered. Of the latter, the cyanide process, to 

 which we owe the extraordinary production of gold 

 in the Transvaal, is dealt with at considerable length 

 in the eighth chapter. 



Silver, now of much less importance than gold, 

 since it is no longer in use for the standard coinage 

 of most countries, occupies only about half the space 

 given to the nobler metal. 



The alloys, compounds, and ores of silver are first 

 discussed, and then methods of extraction. The 

 important methods are described, and even those 

 which have become, or are becoming, obsolete receive 

 fitting attention. The time-honoured patio process in 

 Mexico, where the climate and other conditions 

 were specially favourable for its success, which has 

 produced many millions sterling of the metal, has 

 evidently had its day, is being replaced by the modern 

 cyanide process, and is now mainly of historical 

 interest. The same is true of other "wet" processes 

 in many silver-producing districts. 



.•\n entire chapter is devoted to the processes 

 employed in the refining of gold .nnd silver, operations 

 dealing annually with enormous values. Thus gold 

 to the value of 50,000,000/. is refined every year by the 

 sulphuric-acid process, 12,000,000/. by the chlorine 

 process, and about 4,000,000/. by electrolysis. 



The chapters on assaying, minting, and the manu- 

 facture of gold and silver wares are written with 

 great clearness, and give the best brief and trust- 

 worthy account which has yet been published on these 

 subjects. They will be read with interest by both 

 technical and non-technical readers. Platinum, 

 although not usually included in the term " precious 

 metals," yet, being in common use and more valuable 

 weight for weight than gold, has been rightly given 

 a place in the book. The condensed account given 

 of it deals with its occurrence, properties, alloys, 

 extraction, purification, and assay. 

 NO. 2092, VOL. 82] 



The volume concludes with a series of statistics re- 

 lating to the production and consumption of the 

 precious metals. 



The accounts of the various operations by which 

 these metals are extracted from their ores and re- 

 fined or adapted for minting or industrial use, although 

 brief, arc clear and accurate, and the essential points 

 in each process on which its success depends are 

 carefully set forth. A valuable feature, too, is the 

 chemical reactions and changes which occur in the 

 operations, and the principles on which they are 

 based, which appear under each metal. 



Dr. Rose is to be congratulated on his book. He 

 has succeeded in compressing within the limits of 

 295 pages an excellent summary of the metallurgy of 

 gold, silver, and platinum, marvellous in conciseness, 

 quite up-to-date, and without the omission of any- 

 thing of serious importance. 



It deserves many readers, and can be strongly re- 

 commended to metallurgical students, by whom it can 

 be studied with advantage before or at the same time 

 as the larger text-books. W. G. 



FLOWER CULTURE. 

 Beautiful Flowers and how to Grow Them. By 

 Horace J. Wright and Walter P. Wright. Pp. 19S. 

 (Edinburgh : T. C. and E. C. Jack, n.d.) Published 

 in seventeen parts at is. each, or two volumes at 

 los. 6d. each. 



THIS work will take a high place amongst recent 

 publications dealing with the popular and 

 fascinating art of floriculture. The authors have 

 made a selection of the best and most beautiful 

 flowers for cultivation in the garden and greenhouse. 

 These flowers, numbering 100 in all, are illustrated 

 in full-page coloured plates, which are excellent re- 

 productions of flower paintings by such well-known 

 artists as Beatrice Parsons, Eleanor Fortescue Brick- 

 dale, .'\nna Lea-Merritt, Hugh L. Norris, Lilian 

 Stannard, Margaret Waterfield, .\. Fairfax Muckley, 

 and Francis E. James. 



Such a collection affords a very valuable guide to 

 amateurs as to which flowers are likely to give them 

 most pleasure, and, in the majority of cases the kinds 

 presented will be found amply suflicient for their 

 study ; but, not only so, the plates will prove useful in 

 two further directions. In the first place, many of the 

 pictures depict the particular flowers grouped with 

 other kinds with which they harmonise perfectly ir» 

 the garden, and, in the second place, as the paintings 

 were in most cases prepared from first-class speci- 

 mens, they set before the amateur a high standard 

 of culture he will do well to emulate. Both these 

 lessons are given in such plates as a " Bed of La 

 France Roses," "Dwarf and Climbing Roses, with 

 Zonal Geraniums," "Madonna Lily {Lilium candi- 

 dum) and Roses," " Pyrethrums and Lupins," " Fox- 

 gloves and Poppies," "Asters, Phloxes and Sweet 

 Peas," " Hippeastrums," "Single Dahlias," "Rose- 

 arch and Campanulas," " Hardy Chrysanthemums," 

 and "Water Lilies." In certain others a supremely 

 satisfactory result is obtained by showing a single 

 plant depicted in all its glory, such, for instance, as 



