Jan. 1 6, 1890] 



NATURE 



245 



technic " a higher department, providing for the more 

 specialized wants of each locality. This will be a work 

 which no body is so well fitted to undertake as the great 

 Institute which has been a pioneer in higher technical 

 instruction. Such, it appears to us, is the true solution of 

 the question of the relations between the Charity Com- 

 missioners' scheme and the City and Guilds of London. 



One word of caution in conclusion. The new institutes 

 should be allowed to grow, and not be started on too 

 ambitious a scale at first. Local wants change, and the 

 institutes should develop in harmony with their changes. 

 This is the lesson of the old Mechanics' Institutes and 

 Athenseums. The lesson is repeated in the newer experi- 

 ments of Mr. Hogg's Polytechnic, and the People's Palace. 

 We do not want to begin with erecting huge shells of 

 bricks and mortar, hoping that life will somehow come 

 into them after a time. The life first, then the buildings, 

 to grow as it expands and deepens — that surely is the law 

 of nature. " Several architectural white elephants " is 

 the dismal but suggestive forecast of a writer in the 

 Charity Organization Review, on the supposition that this 

 law is violated. If these warnings are neglected, the pro- 

 moters of the movement will be merely courting failure, 

 however good their intentions may be. And they will 

 have failed because " they were not poets enough to 

 understand that life develops from within." 



ASSAYING. 

 Text-book of Assaying. By C. Beringer and J. J. Beringer. 

 (London : Griffin and Co., 1889.) 



THIS text-book marks an important departure in the 

 literature of assaying. The authors abandon the 

 dreary details of traditionary methods, and attempt with 

 success to rationalize the art of the assayer, rather than 

 to follow the usual course of reproducing " dry " assay 

 methods and elaborate classifications of processes the 

 interest of which is only historical. Assaying is here 

 treated, in a broad sense, as the determination, by analy- 

 tical methods, of components of ores and of intermediate 

 or finished metallurgical products. Such compounds may 

 be either of value in themselves, or important from being 

 valuable or injurious in the operations of smelting, or in 

 adapting the metals for use. 



The methods of the authors, and the measure of success 

 which they have attained, may be fairly judged by their 

 treatment of copper, ead, and iron. Copper ores and 

 furnace materials are still sold in the English market by 

 the " Cornish" assay. This antiquated method of assay- 

 ing has really no claim to retention, now that more 

 trustworthy methods are well known, and the authors give it 

 but little prominence. They, however, repeat the fallacious 

 argument of its apologists by stating that " it gives the 

 purchaser an idea of the quantity and quality of the metal 

 that can be got by smelting." The Cornish assay does 

 not deserve even this modified approval, as the results it 

 affords neither represent the actual amount of copper 

 contained in the ore, nor the proportion of metal which can 

 be produced by smelting, and several expert assayers, 

 working on portions of the same samples, will obtain 

 results which vary in the most erratic way. Fortunately 

 for those who may be guided by this text-book, its authors 

 proceed to describe assaying processes which are really 



well calculated to give trustworthy indications as to the 

 quantity and quality of metal obtainable from ores. 

 These are to be found in well proved " wet " methods of 

 determining actual copper contained in ores as well as 

 the components that interfere with the extraction and 

 the quality of the metal. In describing these methods, 

 ample information is given for the guidance of the smelter 

 under the varying conditions of the metal's occurrence. 

 While passing shortly over the Cornish assay, the authors 

 judiciously omit such clumsy " wet " methods of assay as 

 the direct titration by cyanide of potassium, which is re- 

 tained in some recent books of standing, although it has 

 been abandoned by most skilful assayers. On the other 

 hand, titration by cyanide of potassium after separation 

 of the copper from interfering metals, and the assay by 

 electrolysis, leave little to be desired in rapidity and 

 accuracy, and to these due prominence is given. Failing 

 reasonable manipulative skill, no assay can be accurate, 

 and the expertness demanded by those who conduct the 

 " dry " or Cornish assay is not more easily acquired than 

 is the analytical skill needed for better "wet" methods. 

 In. an assay method giving accurately the amount of metal 

 actually present in the ore, the metallurgist has a sure 

 basis for calculation, the results of which can be brought 

 under the control of his experience as to the losses of 

 metal in operations on a large scale. The results of the 

 Cornish assay, with all its inherent uncertainty, have 

 equally to be judged in the light of the smelter's experience 

 as to what the final " out-turn " will be. In lead, again, 

 the dry assay is usually treated in books on assaying with 

 much elaboration, which is no longer useful, if it ever was. 

 It gives results that indicate neither the actual amount of 

 metal contained in the ore, nor the amount which will be 

 produced by smelting, and like the Cornish assay for 

 copper is most unsatisfactory for guidance in smelting. 

 The wet methods of lead assaying which are described 

 are convenient and trustworthy, while the only practically 

 useful methods of dry lead assay are given in sufficient 

 detail. In the assay of iron ores we find dry methods 

 entirely omitted. The wisdom of this cannot be doubted, 

 for the want of exactitude which is characteristic of the 

 dry assay of copper and lead is still more marked in the dry 

 assay of iron. Processes of wet assay capable of giving 

 prompt and strictly accurate results are available, and 

 these are fully described. 



The plan of subordinating or ignoring unsatisfactory 

 methods of assay, while giving prominence to those 

 which have proved to be trustworthy, runs through the 

 treatment of methods of assaying the other metals, as 

 well as estimating the components of ores which are not 

 usually dealt with in books on assaying. Among the 

 latter are silica, the earths, sulphur, arsenic, and phos- 

 phorus. These demand study by the metallurgist, to 

 whom, under either the necessity of " fluxing " them away, 

 or of minimizing their interference with the purity of the 

 metals, their ready and accurate determination is a matter 

 of the greatest importance. The details of assaying the 

 precious metals, though hardly sufficient for adoption in 

 the assay of bullion in a mint, are all that is needed in a 

 works. 



The authors have clearly not been content to merely 

 record published processes, but in order to add to the 

 completeness of their work have given unpublished 



