2IO 



NATURE 



[July 15, 1875 



treats of the physical properties of metals. Thus a gene- 

 ral but comprehensive view of the subject of Elasticity is 

 given, with ample references to the works of Wertheim, 

 Kupffer, Styffe, and others. Tresca's experiments on the 

 flow of metals are also briefly described, and " Tensile 

 strength" has "received due attention. Graham's experi- 

 ments on the occlusion of gases by metals are described 

 at some length. 



The matter relating to the composition, fusibility, and 

 character of slags, has been re-arranged. 



As plumbago crucibles are now so extensively used, the 

 question of the suitability of different kinds of graphite 

 for their manufacture has become of much importance. 

 A valuable table of analyses of graphite of various quali- 

 ties from different localities is therefore given, and the 

 machinery used by Messrs. Morgan in their well-known 

 crucible works is illustrated by excellent drawings. The 

 apparatus devised by Ste. Claire Deville for obtaining high 

 temperatures is now frequently employed in laboratories, 

 and the description of the methods of making the cru- 

 cibles of carbon, lime, magnesia, alumina, and bauxite will 

 be of much service. Deville's blast furnace is described, 

 but we could have wished that, in the interests of metal- 

 lurgical research, some account had been given in this 

 place of the oxyhydrogen blowpipe, and of the apparatus 

 by means of which he melted platinum. 



Care has been taken to collect the recently discovered 

 facts relative to the calorific power and calorific intensity 

 of fuel, and these are specially considered with reference 

 to furnace tempeiatures. The section devoted to Pyro- 

 metry is excellent, and Weinholt's classification of the 

 principles on which the instruments have been con- 

 structed has been adopted. 



The question of the utilisation of peat and of the possi- 

 bility of substituting it for coal in metallurgical and other 

 manufacturing processes, has of late particularly engaged 

 public attention in this country. Dr. Percy has therefore 

 collected " such evidence as may enable the reader to 

 arrive at a satisfactory judgment on that question," and 

 forty-six pages are devoted to the consideration of cutting 

 peat, together with its mechanical treatment, condensa- 

 tion, and desiccation. We may quote some of Ur. 

 Percy's general conclusions as to its use as fuel. He 

 observes that, " so far as the suitability of peat for metal- 

 lurgical purposes is concerned, we may not unreasonably 

 conclude that it could be widely substituted for coal with 

 success ; " but he states as his conviction that peat can 

 only compete with coal in countries where the cost of pro- 

 duction and carriage of peat is relatively very low and the 

 price of coal is relatively very high. 



More than 200 analyses of coal from various paits of 

 the world are given, and we may mention as an indication 

 of the care which has been taken to render the section 

 devoted to coal as complete as possible, that Von Meyer's 

 recent investigations as to the nature of the gases disen- 

 gaged from certain varieties, and Fleck's table showing 

 the action of weathering on the chemical composition of 

 coal, are recorded at some length. Valuable remarks as 

 to the various sources of errOr in the analysis of coal are 

 given, but we venture to think that students would have 

 been grateful for some account of the methods of analysis 

 and details of manipulation. 



The author next treats of charcoal, and an account of 



Dromart's process for charring in circular piles by firing at 

 the bottom has been added to the descriptions of the 

 various processes contained in the former volume. Refer- 

 ence is also made to the methods of preparing brown 

 charcoal and " torrefied wood," and the section concludes 

 with theoretical considerations concerning their use. 



In the new matter^' relative to coke, the various methods 

 of desulphurisation are treated at some length, and, in 

 considering i the economic products generated during 

 coking. Dr. Percy gives much evidence as to the working 

 of Pernolet's oven ; but he concludes, as in the case of 

 many other metallurgical operations, by pointing out that 

 the evidence as to the advantages of the process " is not a 

 little conflicting." A new article has been added on the 

 preparation of peat- charcoal, with reference to the em- 

 ployment of which the author observes " that as yet the 

 use of peat-charcoal in metallurgical operations in Great 

 Britain is either very restricted or must be kept rigidly 

 secret." 



The consideration of one or two questions of practical 

 importance in connection with the subject of fuel is 

 reserved for the conclusion of the volume. 



The author, in treating of the preparation of peat for 

 fuel, makes some observations on patents generally which 

 deserve notice. He says : " Should any person of ordi- 

 nary intelligence^ be disposed to wade through the dreary 

 specifications of patents relating to the preparation of peat 

 for fuel, he will perceive that frequently the same thing 

 has been patented several times, and that in not a few 

 cases the patentees have displayed astounding ignorance 

 of the subject." He suggests as a remedy that " a tribu- 

 nal for the administration of patent law " should be esta- 

 blished. " The expenses of such a tribunal could be 

 defrayed .... out of the large surplus income, exceed- 

 ing 50,000/., arising from the duties and fees paid by 

 patentees." The authority of such a court would doubt- 

 less have a very beneficial effect ; but we may point out 

 that the sum above named would probably be very mate- 

 rially reduced by its intervention, and that the vigilance 

 and remuneration of the tribunal might each tend to 

 diminish the other. Dr. Percy calls attention to the 

 scheme proposed during the present session by the Lord 

 Chancellor, who suggests the appointment of five addi- 

 tional commissioners of patents, without giving them any 

 remuneration whatever for their services ! 



Among the illustrations are plans and sections of 

 Ekman's peat kiln, of Echement's pile for making brown 

 charcoal, and at the end of the volume there are nine 

 folding plates, some of them coloured, giving complete 

 working drawings of Siemens' gas producer and regene- 

 rative gas reheating furnace, and of Coppee's coke oven, 

 in which even the forms and dimensions of the fire-bricks 

 are shown. The drawings throughout the volume are 

 admirable, and, as is the case in all Dr. Percy's works, 

 are drawn to scale. 



We think that it is a matter for congratulation that the 

 author's labours have been devoted to rendering the intro- 

 duction to Metallurgy as complete as possible, before 

 considering metals not yet touched upon, which would 

 doubtless have been more attractive work. Throughout 

 this, as in former volumes, the slightest aid has been 

 carefully acknowledged, and the relative merits of dis- 

 coverers are most conscientiously apportioned, in Dr. 



