March i, 1894] 



NA TURE 



411 



and details of boiler construction and design are 

 discussed. 



It is a matter for regret that from so good a book a 

 certain number of errors could not have been eliminated. 

 Thus, in speaking of the pitting of boiler plates below 

 the surface of the water, the author states that in con- 

 tact with the heated portion of the plate, the water gives 

 up its dissolved air in contact with the surface of the 

 metal, and that the bubbles there remain until large 

 enough to rise, and he considers that during this period 

 of rest the "nascent" oxygen which they contain will 

 attack the iron. The idea that oxygen driven out of 

 solution by the action of heat possesses the powers 

 attributed to the nascent condition, will come as a sur- 

 prise to his chemical readers. And again, on p. 6i it is 

 stated that in the lungs the process of slow combustion 

 is continually proceeding. In an age of specialism it is 

 unlikely, and perhaps undesirable, that an author should 

 speak witli equal authority as engineer and physiologist. 

 Reference to any modern text-book of physiology would 

 have made clear the fact that diverse as may be the 

 opinions as to the actual field of oxidation, the author 

 appears solitary in selecting the lungs as the sphere of 

 action. 



The collection of formulas put forward by various 

 authorities for calculation of the calorific value of fuel 

 from its chemical composition is very complete, but the 

 author might have insisted more strongly than he has 

 upon the errors inseparable from any such calculated 

 heat values, which are due to our present ignorance of 

 the molecular groupings in coal, and the thermal changes 

 attending its formation. 



An amazing confusion of idea is exhibited in the state- 

 ment made on p. 69, " that gun-cotton ignites so readily 

 that it could not be used for ammunition until it was dis- 

 covered that the admixture of camphor or nitroglycerine 

 raised this temperature." In the table of temperatures 

 of ignition, on the same page, the ignition point of coal is 

 given at 600° F. ; this, on the evidence of recent experi- 

 ments, is too low. 



In the valuable chapter on heat transmission, no men- 

 tion is made of one of the chief sources of loss in the 

 passage of heat from the furnace to the water, namely, 

 that the burning furnace gases are extinguished by con- 

 tact with the comparatively cold surface of the plates, 

 with the result that the flame never comes in contact with 

 the metal, a layer of unburnt gas of very low conductivity 

 existing between flame and plate ; and this not only im- 

 pedes the passage of heat to the water, but the gas 

 creeping along the surface of the metal often escapes 

 combustion, both in the furnace, combustion chambers, 

 and tubes. 



Coming to the engineering portion of the book, there 

 is much which will excite comment from practical men. 

 In the basic Bessemer steel process using phosphoric 

 pig-iron, the purity of the blown metal is usually judged 

 by the bath sample " fracture," which is quite as easy to 

 gauge as a sample from the open-hearth working, and 

 the procedure given in paragraph 6, p. loi, is at vari- 

 ance with every-day practice. Again, in describing the 

 acid Siemens-Martin process, on p. 103, the author speaks 

 of adding 25 per cent, scrap-iron, the ordinary practice 

 being to charge steel scrap with the pig-iron before melt- 

 NO. 1270, VOL. 49] 



ing. In fact, scrap-iron could not be used in any quan- 

 tity in this process, on account of the phosphorus and 

 sulphur often contained in it ; and it is the custom in 

 most works to pick out all the iron found amongst the 

 steel scrap for use in the Siemens-Martin furnace. 



On p. 107 there is an excellent paragraph on cold 

 bending, which contains valuable suggestions ; but the 

 remark that the bending of samples after annealing is 

 valueless, may be objected to. The obvious reason of 

 doing so is to bring the sample to the same condition as 

 the finished article, and it is a common practice to specify 

 that flange plates, or plates which have to be worked in 

 any way, shall be annealed as a final process to bring 

 them to a uniform condition ; they may have been rolled 

 at various temperatures, in which case the tensile and 

 elongation tests would vary considerably. Nor will Mr. 

 Stromeyer's remarks upon drift tests meet with the 

 general approbation of railway engineers. Surely, also, 

 the first paragraph on p. 122, when considered in con- 

 junction with the remarks on annealing made on p. 107, 

 are of a contradictory nature .'' 



The opinions expressed in the first paragraph of p. 156 

 are not justified by results of recent experiments, and the 

 percentage of failures on the weld is not nearly so high 

 as one would be led to expect from the experimental 

 figures given on p. 157. 



The tools described as being in use in boiler shops, on 

 p. 182, are of an old-fashioned type, for special machines 

 with three or more spindles capable of drilling up to 

 120 tube holes per day of nine hours, without any pre- 

 paration of the plates, such as punching or drilling small 

 holes, have been in use in most shops for a considerable 

 period. The statement made on p. 237, that fitting a 

 sufficient number of stay tubes will overcome the trouble 

 consequent upon forced draught, is open to criticism, as 

 it is not borne out by facts, and has indeed been the 

 cause of considerable trouble in boilers. 



It would have been better on the whole, considering 

 the large number of books which now exist on design, to 

 have curtailed the space devoted to this branch of the 

 subject, which, although no doubt useful to the young 

 draughtsman, might with advantage have been omitted 

 from Mr. Stromeyer's book. 



These are minor and technical criticisms of an excel- 

 lent work, exhibiting signs of much industry in com- 

 pilation. The author is to be especially commended for 

 his habit of reference on all occasions to the source of 

 information. 



OUR BOOK SHELF. 



Chapters on Electricity. By Samuel Sheldon, Ph.D. 



(New York : Charles Collins, and the Baker and 



Taylor Co.) 

 In the preface the author states that "these chapters on 

 electricity, prepared for and included in the fourth revised 

 edition of Olmsted's ' College Philosophy,' are here 

 offered in a separate volume." The chapters deal in much 

 the usual way with the stock work commonly found in 

 elementary text-books on magnetism and electricity. The 

 writing, however, appears to have been carefully done ; 

 the general style is clear and concise, but a little more 

 explanation would, inmany cases, have added to the clear- 

 ness and, in a few cases, to the accuracy of the work. 



