50 



NATURE 



[November 17, 1904 



an analytic function of its arguments? or does the 

 word analytic mean regular? and what is the meaning 

 of expressed? Again, on p. 98 : " This transformation 

 of the variables has only involved algebraic processes." 

 The processes in question consist in reverting certain 

 power series ; now a power series is an entirely symbolic 

 thing unless we have very simple rules for the law of 

 its coefficients ; how can the reversion of a power 

 series in general be regarded as a practicable process 

 likely to aid the effective determination of the integrals 

 of a differential equation? and at any rate it does not 

 seem fair to describe it as an algebraic process. More- 

 over, apart from such indefiniteness, and passing over 

 such phrases as (p. 24) " where t is a constant so small 

 that its square may be neglected," there is the question, 

 apparently unconsidered in this book, of how far Lie's 

 propositions can be proved for functions which are not 

 analytic, in regard to which various investigations are 

 already forthcoming. 



But we gladly turn from such criticisms to remark 

 again on the merits of the book, choosing two random 

 examples, one of the practical spirit in which it is 

 written, the other of the author's eye for a neat result. 

 On p. 256 the author frankly uses the known theorems 

 as to forces in three dimensions to abbreviate the re- 

 duction of the equation of a linear complex. On 

 p. 243 the author arrives at the theorem that Ampere's 

 partial differential equation of the second order is re- 

 ducible by a contact transformation either to s = o or to 

 rt—s- = o, according as it possesses two distinct systems 

 of intermediary integrals or only two coincident 

 systems. In conclusion, we would express our admir- 

 ation for the form and printing of the volume. 



H. F. B. 



TECHNOLOGICAL CHEMISTRY. 

 The Industrial and Artistic Technology of Paint and 

 Varnish. By A. H. Sabin, M.S. Pp. vi + 372. 

 (New York : John Wiley and Sons ; London : Chap- 

 man and Hall, Ltd., 1904.) Price 12s. 6d. net. 

 Food Inspection and Analysis. By Albert E. Leach, 

 S.B., Analyst of the Massachusetts State Board of 

 Health. Pp. xiv + 787. (New York: John Wiley 

 and Sons; London : Chapman and Hall, Ltd., 1904.) 

 Price 3 IS. 6d. net. 

 (1) ' I "HIS is a gossipy, pleasantly discursive volume, 

 J- the style of which will be indicated when we 

 remark that the book is prefaced by an extract from 

 Quintilian, and closes with a poetical quotation. It 

 treats, generally in untechnical and even colloquial 

 language, of varnishes and paints, their history, 

 fabrication, and uses. Principles, not formula;, are 

 usually given by the author ; the book is in no sense 

 a collection of recipes. 



If there is not much of strictly scientific value in the 

 treatise, there is a good deal which is of practical 

 interest. The chapter upon the protection of metals 

 against corrosion, for instance, may be recommended 

 to the notice of engineers, and also that on the coating 

 of water-pipes. As regards this latter question, the 

 author points out that the essential feature of the 

 " .'\ngus Smith process " has been misapprehended in 

 NO. 1829, VOL. 71] 



modern practice. Dr. Smith's treatment resulted in 

 a varnish or " enamel " of linseed oil and coal-tar 

 pitch being baked on to the cleaned surface of the pipe, 

 the oil oxidising more or less completely during the 

 operation. The modern substitute for this is, too 

 often, a mere dipping of the pipe in crude tar, or in 

 tar diluted with " dead oil." From the wording of the 

 original patent this process may, on a technicality, pass 

 under Angus Smith's name; but our author has no 

 doubt that if the inventor were living he would con- 

 demn the whole thing from beginning to end. It is 

 " adulterating his invention and stealing his reputa- 

 tion." 



Mr. Sabin describes a process of his own, which has, 

 he tells us, been successfully applied to large pipe- 

 lines in America, and is in use in the United States 

 Navy for the protection of heavy copper mains. It is 

 evidently based upon a study of the Angus Smith 

 process. It consists in applying to the pipes a thin 

 coating of a mixture of linseed oil and asphaltum, and 

 afterwards heating the pipe to 400° F. until the oil 

 is completely o.xidised. The product is said to be a 

 hard, elastic enamel. One result is that, whereas the 

 aforesaid copper mains had formerly an average " life " 

 of about six months, they have now lasted three or 

 four years, and their ultimate durability is not yet 

 determined. 



There is some curious lore in the author's historical 

 summary. The connection between electricity and 

 " Berenice with the golden hair," between varnish and 

 the Queen of Cyrene, is a good example of etymological 

 ramifications. One quaint recipe of 1520 is worth 

 quoting : — 



" A most excellent varnish for varnishing arque- 

 buses, crossbows, and iron armour : Take of linseed 

 oil two pounds, sandarac one pound, Greek pitch two 

 ounces. Boil the oil, then dissolve in it the other in- 

 gredients, and strain through a much-worn linen 

 cloth ; and when you wish to use the varnish, scrape 

 and polish the work and heat it in a hot oven, because 

 that is the best place to heat it . . . then lay it on 

 thinly with an instrument of wood, so that you may 

 not burn your fingers, and it will make a beautiful 

 changing colour. 



" And if you supplied the place of Greek pitch with 

 naval pitch, I think it would make the work black 

 when you varnished it." 



The treatise can be read with profit either by the 

 manufacturer who knows little of chemistry, or by the 

 chemist who wishes to know something of paint and 

 varnish technology. 



(2) There is a Madras story of a native woman, who, 

 charged with possessing illicit salt, would offer no 

 defence ; wherefore she was about to be mulcted in 

 the sum of one rupee. Before closing the case, how- 

 ever, the magistrate thought he might just as well 

 satisfy himself that the substance really was salt, and 

 forthwith proceeded to taste it. Thereupon the lady 

 raised her voice in a very effective interjection : "Not 

 only," said she, " not only does the sahib fine me one 

 rupee, but lo ! he cats the ashes of my dead husband." 



Fortunately for magistrates, such appeals to the 

 palate are rarely either necessary or sufficient, nowa- 

 days, for disposing of legal cases relating to the 

 identity and purity of foodstuffs. Much more cum- 



