AGRICULTURAL CHEMISTRY — AGROTECHNY. 803 



"After the cupric sulphate aud calcic oxid have been brought together, a 

 slight delay in stirring the mixture does not materially affect the physical state 

 of the precipitate. Long continued stirring of Bordeaux mixture does not mate- 

 rially affect the physical state of the precipitate. The Bordeaux mixtures em- 

 ployed in practice fall into one or another of three types: (a) 'neutral' Bor- 

 deaux mixtures of which Woburn Bordeaux mixture is a ti-ue type and 'acid' 

 Bordeaux mixture a proximate type; (b) slightly alkaline Bordeaux mixtures — 

 neutral Bordeaux mixture is a good example of this class; (c) strongly alkaline, 

 or basic Bordeaux mixtures; in this class belong those Bordeaux mixtures in 

 which the ratio of cupric sulphate to calcic oxid is not greater than 2 to 1." 



An introduction to the chemistry of plant products, P. Haas and T. G. 

 Hill (New York, London, and Bombay, 1913, pp. XII+4OI, figs. 5). — This work ^ 

 is an attempt to provide the botanist and students of botany having some j 

 acquaintance with chemistiy with an introductory account of the chemistry audi 

 biological significance of the more imixtrtant chemical substances occurring in- 

 plants. In some instances micro-chemical, qualitative, and quantitative methods, 

 are included. I 



Its contents include fats. oils, waxes, phosphatids, carbohydrates, glucosids, ■ 

 tannins, pigments, nitrogen bases, colloids, proteins, and enzyms. 



On the demonstration of carotinoids in plants, C. van Wisselingh {K. 

 Akad. Weteiisch. Amsterd<im. Proc. Sect. Sci., 15 (1912), pt. 1, pp. 511-526. 686- 

 692, 693-700; K. Akad. Wetmsch. Amsterdam, Vcrsl. Wis en Xatiiurk. Afdeel., 

 21 {1912). Xo. 1, pp. 370-386, 565-572, 572-579).— Thin article is in three parts. 



I. Separation of carotinoids in crystaUine form. — The results obtained by 

 various investigators in regard to the carotins, or carotinoids, of plants are 

 far from uniform. The microscopical findings are especially divergent and they 

 conflict with those shown by the chemical and physical methods. Some investi- 

 gators believe all carotinoids to be identical. On this account a study was made 

 of the various mici'o-chemical methods, including the potash, dilute acid, and 

 resorcinol methods. 



" The results of the above crystallization experiments point strongly to the 

 frequent occurrence of several distinct carotinoids in a plant." 



II. Behavior of carotinoids with regard to reagents and solvents. — " The 

 reagents by means of which coloration is brought about in carotinoids are the 

 following: Concentrated sulphuric, sulphurous, and concentrated nitric acids, 

 bromin water, concentrated hydrochloric acid with a little phenol or thymol, and 

 iodin in potassium iodid or chloral hydrate solution. All these reagents cause 

 blue coloration except the iodin reagent, which generally produces a green color. 



" In this paper the use of sulphuric acid, bromin water, and iodin in potas- 

 sium iodid solution is dealt with as well as two new reagents for carotinoids, 

 namely, concentrated solutions of antimony trichlorid and of zinc chlorid both 

 in 25 i>er cent hydrochloric acid." 



The list of the organs and plants on which the new reagents were tested were 

 (1) flowers of Trollius caticasiciis, Chelidonium ma jus, Isatis tinctoria. Spar- 

 tium junceum, Thermopsis Janceolata, Cucurbita nvelanosperma. Ferula sp., 

 Asclepias curassavica. Calceolaria riigosa, Dendrobium thyrsiflorum, Iris pseuda- 

 eorus. Narcissus pseudonarcissns, and Lilium crocemn; (2) green leaves of 

 Chelidonium ma jus and Urtica dioica; (3) fruits of Sorbus aucuparia and 

 Solanum lycopersicum; (4) the root of Daucus carota; and (5) algae, viz, 

 Cladophora sp., and Hcematococcus pluvialis. 



III. The leaf of Urtica dioica, the flower of Dendrobium thyrsiflorum and 

 Hcematococcus pluvialis. — In the foregoing communication stress was laid 

 on the fact that the carotinoids present differences in the color and shape of the 



