Chemistry and Physics. 409 



acid, but at 100° is rapidly converted into dextrin. The solution 

 of colloidal cellulose in water is slightly milky, is readily filtered, 

 deposits no precipitate even after several hours' standing and is 

 not altered by boiling. It is slightly orange-yellow in color and 

 rotates the polarized ray slightly to the right. Small quantities 

 of. sulphuric or of nitric acid, of sodium chloride or sulphate, of 

 lead acetate, etc., precipitate it, as is the case with other colloids. 

 Alcohol in large excess acts similarly. Colloidal cellulose does 

 not reduce Fehling's solution, is not colored by iodine, and differs 

 from the achrodextrins in being precipitated by salts added in 

 small quantity. A solution poured on a marble surface previously 

 rubbed with vaseline and well polished, forms brilliant semi-trans- 

 parent pellicles which swell up in water and then dissolve. An im- 

 mersion in sulphuric acid of 60° B. for a short time, or in acid of 

 55° B. for a longer time, causes the colloidal cellulose to become 

 insoluble in water, a small quantity of dextrine being at the same 

 time formed. Nitric acid converts it into nitrocellulose. Parch- 

 ment paper, thin and prepared probably by means of a somewhat 

 weak acid, yields colloidal cellulose to boiling water. But thick 

 paper, presumably treated with a stronger acid is insoluble. 

 Parchment paper therefore may be regarded as a cellular tissue, 

 the pores of which have been filled up with colloidal cellulose. — 

 C. B., cviii, 1258-1259, August, 1889. g. f. b. 



2. Watts' Dictionary of Chemistry, revised and entirely 

 rewritten by H. Forster Morley and M. M. Pattison Muir ; 

 assisted by eminent contributors. In four volumes, vol. i, 752 

 pp. 1888, vol. ii, 760 pp. 1889. London and New York. (Long- 

 mans, Green & Co.). — The first edition of Watts's Dictionary of 

 Chemistry, the publication of which was begun in 1863, will 

 always rank as one of the monumental works of the science. 

 The fifth volume was completed in 1868 and since then a series 

 of supplementary volumes has been issued, the last (1881) being 

 the ninth volume of the entire work. The immense growth in 

 the subject of chemistry in all its branches, however, had already 

 carried it well nigh beyond the possibilities of a single work. 



Sometime before the death of Mr. Watts in 1 884, he had under- 

 taken to prepare a new edition of the Dictionary, but his too 

 early death interrupted the work before more than a beginning 

 had been made and the labor passed to the hands of the present 

 editors. As this new edition is to be limited to four volumes of 

 about 750 pages each, the subjects treated of have been restricted 

 in the first place to those in chemistry proper, excluding the 

 "allied branches of other sciences" which found place in the first 

 edition, and also reserving technical chemistiy for a companion 

 volume to be published under the editorship of Professor Thorpe. 

 Moreover it has been necessary to adopt a rigid system of abbre- 

 viation and condensation so as to compress the almost unmanage- 

 able mass of material into the smallest possible space. Half of 

 the work is now in the hands of chemists and it is needless to say 

 that the great labor has been performed in a faithful, accurate 



