544 



SCIENTIFIC NEWS. 



[June 8, I J 



of 258 pages. The plates, though increased from twelve 

 to fourteen in number, do not wholly supply the want. 



In its original form this work was a manual such as 

 students might use for their own reading while attending 

 a course of lectures and demonstrations. In its latest 

 development it takes rather the place of a book of refer- 

 ence, being a vast and much condensed collection of 

 facts, thoroughly well selected and arranged. It will be 

 used chiefly by those who are already advanced in the 

 study of comparative anatomy — one of the most lascina- 

 ting among sciences. 



A Manual of Practical Assaying. By John Mitchell, 

 F.C.S. Edited by William Crookes, F.R.S., Pres. 

 C.S. Sixth Edition. Longmans, Green and Co. 



Regarded as a standard work, Mitchell's book is very 

 disappointing, and we had hoped to find in the new 

 edition, containing as it does nearly one hundred fresh 

 pages, that revision which it so much requires. Com- 

 paratively little, however, has been done. There is still 

 lacking that personal guidance in the choice of one out of 

 many processes given, which characterised the older 

 work; and the processes themselves are described too 

 often in the words of their original authors, some- 

 what discursively, and conveying the impression 

 that the manual is a collection of newspaper cut- 

 tings, rather than a text-book from the pen of a 

 master. Instances of inaccuracies, and obsolete methods, 

 or terms, are too numerous to mention in full, but we 

 may quote a few by way of example. In the very 

 beginning we find misleading explanations of the laws of 

 chemical combination, as when 16 parts of oxygen are 

 said to combine with i of hj'drogen, or with 207 of lead. 

 On page 154 is given a method of estimating the abso- 

 lute heating power of a coal, " by ascertaining how much 

 the temperature of a room increases by burning a certain 

 weight of fuel in a stove," but the way in which this 

 experiment is to be carried out is not described. 

 Three pages are devoted to Berthier's method of 

 determining the calorific power of fuels by the reduc- 

 tion of litharge, and no hint is given of its absolute 

 unreliability. In the brief description of Wright's 

 (Thompson's) Calorimeter, it is stated that by 

 burning 20 grs. of coal (instead of 30 grs.) under 

 290'! grs. of water (instead of 29,010) in an apparatus 

 weighing 6,6427 grs., a direct reading of evaporative 

 power is obtained ; the instrument is moreover credited 

 with giving very accurate results, while no description of 

 the Favre and Silbermann or other really accurate calori- 

 meters is attempted. The use of Mohr's pinch-cock 

 burette is condemned for use with potassium perman- 

 ganate solution, but no mention is made of glass-tapped 

 burettes. Twice on p. 526 we find NO^ for N^O.. 

 Throughout the work the wasteful habit of breaking the 

 crucible, to extract the button of metal after an assay, is 

 recommended, rather than the equally satisfactory and 

 more expeditious plan of pouring the fluid contents of the 

 crucible into an ingot mould. In regard to the added 

 matter, we are glad to find that much stress is laid on the 

 necessity for accurate sampling, whether of ore or of 

 ingot. Slight additions are made to the chapter on the 

 blow-pipe, while that on iron and steel analysis is practi- 

 cally re-written ; and Blair's elaborate and somewhat 

 costly scheme for the analysis of iron ores is given in full 

 detail, together with Peter's account of the Lake Superior 

 fire assay of copper ores. Of the remaining additions, 

 the accounts of the treatment of gold and silver-bearing 



copper ores, and the greater part of that dealing with the 

 influence of bismuth on the ductility of silver, are doubtless 

 of the greatest interest from a metallurgical point of view, 

 but have little or no bearing on the subject of the book. In 

 fine, if Mr. Crookes would for the next edition undertake 

 the Herculean labour of condensing, systematising, and 

 re-writing the accumulated items of six editions, a volume 

 of half the size and ten times the value would doubtless 

 result, and he would earn the lasting gratitude of all who 

 now feel the want of a reliable guide to practical 

 assaying. 



Journal of the Royal Agricultural Society of England. 

 Annual Report for 1887 of the Consulting Botanist, 

 By W. Carruthers, F.R.S., P.L.S. 



The author shows that the seeds obtained by farmers 

 from seed merchants are still to a great extent bad. A 

 sample of white clover is mentioned as containing 10 per 

 cent, of weeds ; a sample of cocksfoot contained 34 per 

 cent, of other and worthless seeds, and two samples of 

 rye-grass contained respectively 12 or 15 per cent, of a 

 worthless grass known as " Yorkshire fog," which cattle 

 never eat if they can find anything else. These impuri- 

 ties seem, however, in most cases to be traceable to care- 

 lessness rather than] to wilful admixture. One sample 

 of meadow-fescue contained the serious proportion of 20 

 per cent, of rye-grass. 



In seeds perfectly free from admixture, whether acci- 

 dental or intentional, there was also a low standard of 

 germinating power. Of some of the seeds met with in 

 the market, only such proportions as 36, 20, 12, 15, 16, 

 and in one case 6 per cent, have been found to germinate. 

 Such seeds were probably too old, or had been gathered 

 in bad condition. In good samples, on the contrary, as 

 many as 96 and 98 per cent, have been found to grow. 

 We have heard tell of a fraud which is not mentioned 

 here, and which possibly may have fallen into disuse. 

 That is, seeds intended for adulteration were killed by 

 heat before being added to the qualities to be sophisti- 

 cated. 



Some of the samples were ergotised ; the spread of this 

 poisonous parasite, dangerous to man and beast, is 

 greatly to be deprecated. 



Journal of the Royal Agricultural Society of England. 

 Annual Report for \'&%i of the Consulting Chemist. 

 By Dr. J. A. Voelcker, B.Sc. 



The author's attention has been to a very great extent 

 turned to the examination of oil-cakes, both the feeding 

 and the manurial qualities. He concludes that it is im- 

 possible, from analytical results alone, to decide on the 

 purity of a linseed cake. In all doubtful cases a special 

 microscopical examination is necessary. The proportions 

 of sand and of woody fibre may be as high in a 

 genuine linseed cake as in one containing 30 per cent, of 

 foreign matter. The chief adulterants met with are rape, 

 cockle-seed, mill-sweepings, locust-bean, and hemp-seed. 



Dr. Voelcker has also analysed a number of samples 

 of sewage sludge. If we may judge from the figures 

 quoted, we cannot wonder at the low estimation in 

 which such manures are commonly held. All of them 

 have evidently been prepared by some lime process, and 

 in the one where the lime is lowest the sand in compen- 

 sation reaches 34'oi per cent. 



Experiments with basic cinder have been made near 

 Woburn, but owing to the unusually dry weather the 

 results have been unsatisfactor}'. 



