December 28, 1893] 



NATURE 



195 



that, with a few exceptions, where the precipitated 

 barium sulphate is used as a basis or bearer of certain 

 colouring matters, the admixture of ground native barytes 

 has no other object than that of adulteration. As an 

 oil paint it is absolutely worthless. But while we have 

 not a good word to say for ground native barytes, 

 especially when it enters into the composition of oil 

 colours, it is quite otherwise with the precipitated or 

 artificial barium sulphate, which, in our opinion, receives 

 here too scanty a treatment, judging by the little the 

 author says about its preparation. It seems almost as if he 

 had quite overlooked its vast importance. He omits to 

 mention that this pigment is principally made from 

 native barium carbonate, or Witherite, by what apparently 

 is a very simple process ; a process, however, which only 

 in the hands of very few makers furnishes it in that perfect 

 condition in which it finds so large an application in pre- 

 paring the surface of paper for chromo-lithography. It 

 is not, indeed, too much to say that this art largely owes 

 its modern development to the introduction and use 

 of this form of barium sulphate. Passing on to gypsum, 

 we think, from the description given, the reader will re- 

 ceive quite an exaggerated idea of the qualities and im- 

 portance of this substance in its application as a pigment. 

 The author says "its body is not as good as that of white- 

 lead, but it is at least equal to barytes in this respect, 

 and is superior to zincwhite." He also states that it 

 mixes well with either water or oil, and it can be mixed 

 with all other pigments without affecting them. Here we 

 might ask, are these the results of the author's own trials .'' 

 In speaking of its being used very largely by paper- 

 stainers and makers of paper-hangings, he says it is pre- 

 ferred to barytes on account of its having more body 

 when used for that class of work ; " bulk," perhaps, would 

 be a more correct term in this case. We almost suspect 

 that the author, whilst speaking of the use of gypsum as a 

 pigment, really means "satin-white," a substance of some 

 importance to the paperstainer and maker of paper- 

 hangings, which is obtained by precipitating aluminium 

 sulphate with caustic lime, and which is a mixture of 

 calcium sulphate and alumina hydrate. This substance, 

 however, we do not find mentioned in the book before us. 



It deserves to be noticed that, according to the author, 

 gypsum as well as barytes and China clay are used in the 

 finishing of cotton goods. We were under the impression 

 that this nefarious and stupid practice had been given up 

 before now. Strontium sulphate, under the name of 

 strontian white, finds also a place amongst the white pig- 

 ments, and considering the price of strontium minerals, 

 we are not a little surprised to see it stated that strontium 

 sulphate is often sent out as a substitute for barytes. 

 Concluding with the white pigments, we find a very full 

 and interesting account of China clay, and the mode of 

 obtaining it from the natural deposits. 



Regarding the article on Vermilion, it appears to us 

 that the author is under an entire misapprehension as to 

 the merits of the dry and wet methods of its preparation. 

 It is incorrect to say that the Chinese product is finer and 

 more brilliant in tone than that made in Europe. The 

 vermilion made at present in Europe by the sublimation 

 process is quite equal to, if not better than, the Chinese ; 

 but, as regards colour and fineness, the wet-process ver- 

 NO. I 26 I, VOL. 49] 



milion is far superior to either, and is superseding the 

 former. 



We should have thought it hardly worth while to men- 

 tion that the chromates of mercury and silver had been 

 proposed as red pigments, and still less the chromate of 

 copper, which, according to the author, is a dark red (?) 

 coloured body. Under chrome-green we notice that the 

 author takes " Guignet's green " to be chromic oxide, 

 whilst it really is a hydrate of chromium oxide, and 

 the chemical formula he gives for its formation is, of 

 course, quite wrong. 



In the article on Ultramarine we notice misspellings 

 of the names of authors, and R. Hoffmann, for instance, 

 is throughout referred to as " Hofmann." 



The foregoing remarks have already taken up so much 

 space, that we cannot find room for our comments on the 

 remaining chapters dealing with the colours, and we must 

 conclude here, but not without calling attention to the 

 latterpart of the book, which treats of paint vehicles, oils, 

 resins and varnishes, and gives a very full and interest- 

 ing account of these materials. The description of the 

 manufacture of oil varnishes is particularly valuable, as it 

 gives an exact account of processes which are usually 

 guarded with much secrecy. 



BRITISH FUNGUS FLORA. 

 British Fungus Flora; a Classified Text-book of Mycology. 



By George Massee. Vols II. and III. (London : Geo. 



Bell and Sons, 1893.) 

 T T was originally estimated that this work would be 

 completed in three volumes, but, as we pointed out in 

 our first notice, this was practically impossible. A notice 

 now accompanies the third volume, to the effect that a 

 supplementary volume will speedily be published in 

 conclusion of the work. The second volume continues 

 the Hymenomycetes, which occupy 268 pages also of 

 the third volume, so that two and a half volumes are 

 occupied by the Hymenomycetes, leaving 220 pages for 

 the Hyphomycetes, which bring the third volume to a 

 close. It is only necessary to enumerate the remaining 

 orders to appreciate the difficulty of completing even with 

 a fourth volume. There are all the Ascomycetes, which 

 occupied in Cooke's "Handbook" an equal number of 

 pages to the Hymenomycetes ; and supposing the increase 

 to have been in the same ratio, it may be conjectured 

 that this order (including the Discomycetes) cannot be 

 compressed into less than two volumes. For all that 

 remains afterwards, there will not be so much necessity. 

 There would be the Sphceropsidece and Melanconiece, 

 which are of minor interest, although numbering perhaps 

 700 species. The Phy corny cetece, which have recently 

 been the subject of a volume, by the same author, as 

 " British Fungi, Phycomycetes, and Ustilagineae." 

 Hence they may be dispensed with. The Uredinece, 

 which, with the Ustilaginecz, formed a volume by C. B. 

 Plowright in 18S9, have had so few accessions that a 

 revision is not imperative. The Myxo/iiycctes, which 

 occupied a monograph by G. Massee in 1892, is all- 

 sutScient. As to the Saccharomycetes and the Schizo- 

 mycetes, the little volume by W. B. Grove, dated 1884, 

 would furnish an introduction, and would be fairly 



