REACTION-IN. l 1 3NSITIES Willi BACH AGENT AND REAGENT. 



101 



Many interesting and unexpected peculiarities will 

 be found upon examination of the foregoing table. For 

 instance., potassium nitrate is inert with the starch of 

 lAlium candidum, while potassium nitrite causes com- 

 plete gelatinization in 1 minute; and while the former 

 has been found to be inactive with this starch, it is re- 

 corded by other investigators as being active in relation 

 to the starches of Triticum and Zea. This latter pecu- 

 liarity is noted in the ease of tannic acid. The sul- 

 phides of potassium and sodium arc very active, but 

 the sulphide of calcium is inactive. Strontium nitrate 

 gelatinized 98 per cent of the starch in 3 minutes, while 

 strontium bromide required 30 minute- for the same 

 effect; but the corresponding potassium salts showed a 

 reversal of reaction-intensities. Barium chloride is very 

 at five, but barium nitrate is inactive; and zinc chloride 

 and zinc sulphate -how the same characteristics. Sodium 

 hydroxide and hydrochloric acid when in separate solu- 

 tions are very active, but sodium chloride is inactive, etc. 



A detailed study of the specific properties of the ions 

 and molecules of these reagents in their relations to the 

 starch molecules in the phenomena of gelatinization, and 

 also in the subsequent disintegration processes, is of 

 prime importance, and not only in the elucidation of 

 the chemistry of the starch molecule, but also in colloidal 

 chemistry in general. Inasmuch, however, as the funda- 

 mental object of these gelatinization experiments has 

 been the differentiation of starches from different em es 

 by peculiarities of the quantitative and qualitative relic- 

 tions, as this object has been attained without reference 

 to the precise natures of the chemical reactions involved, 

 and as detailed study of parts played by the different 

 ions and molecules is therefore needless for the fulfil 

 ii n 1 1 1 of the purposes of the investigation and would lead 

 us far beyond the limitation- of space in this memoir, 

 further study of this nature has been omitted. 



Variable Relationships or the Reaction-intensi- 

 ties AS REGARDS SAMEN ESS, I \ l'KI.'\ tATENESS, ETC. 



That we arc dealing in the .-tar, lies from different 

 plant sources with stereoisomers, and not merely with 

 mechanical mixtures of varying proportion- of -■ 

 11 



kinds of starch or with starches that differ bi 

 varying impuril need by variations ob- 



] hip- of the 

 parental and hybrid starches with different re;: 



harts of both A and B I. Were then 



instance, merely mechanical mixtures of varying pro- 

 portions representing the parental and hybrid starches, 

 respect tvely, and a given reagent, >und that 



til- reactivities are in the order of seed parent, pollen 

 parent, and hybrid, and that if there were u 

 miii, ■titration- of the same reagent, v. tion- 



tntensities would be incn I, the order of 



reactivity would noi be changed. Moreover, it would 

 lie expected that with all reagents the same order of 

 reactivity would be found. It also -cents clear, if im- 

 purities played any important part, that when closely 



I reagents, such as potassium and sodium hydroxide, 

 are used, while some differences in mean reaction-inten- 

 sity might lie expected, there ,-hould lot he a chan 



the order of react iv it v. The opposite is shown l>v these 

 charts. Thus, Charts A 6, AT. As (chloral-hydrate, 

 chromic-acid, and pyrogallic^acid reactions) of the Ama- 

 ryllis-BrunsvigiarBrunsdonna reactions show in the 

 chloral-hydrate reactions that the order of rea 

 Brunsdonna sandera, l'>. sandera alba, Amary 

 donna, and Brunsvigia josephina, the first two showing 

 a markedly greater reactivity than the second two. and 

 the reactions of the members of each pair beii 

 alike. In the chromic-acid reaction- all four are s 

 so that while there is marked differentiation with chloral 

 hydrate there is none with chromic acid. In the pyro- 

 gallie-acid reactions there is somewhat better differen- 

 tiation than in the chloral-hydrate reaction-, and 

 an entire change in the order of reactivities, her I 

 order being Brunsvigia jt><< i /i/iin<' . Amaryllis belladonna, 

 Brunsdonna sandera alba, and 11. sandera, Vn<- hybrids, 

 as in the chloral-hydrate reactions, being nearly the same, 

 but the parental starches well differentiated from each 

 other : moreover, here the parental starches are more 

 reactive, while in the chloral-hydrate reactions they are 

 less reactive. CorrespondiitL' phenomena are observed 

 in instances where the reagents are chemically very 

 closely related, as in the cases of potassium and sodium 

 hydroxide, potassium and sodium sulphide, and mineral 

 . which would seem to eliminate the possibilit 



being due to mechanical mixtures of 

 different starches or to impurities. The Amaryllis 

 -,t exhibits with potassium hydroxide no noticeable 

 differences in the reacti\ ities of the four starches, b< 

 probably of the great rapidity of gelatinization, and little 

 or very little difference is found in the reactions with the 

 nitric, sulphuric, and hydrochloric acids. Bui wit! 

 dium hydroxide and all of the other reagents, excepting 

 chromic acid, one or more of the reactivities will be 

 found at variance with the others; and. r, the 



relationships of order of reaction-intensity arc of the 

 most varied character. Thus, in the sodium hydroxide 

 chart the order of reactivity is Amaryllis belladonna, 

 Brunsvigia josephina, Brunsdonna sandera alba, and 

 /?. sanderm, wh r is entirely different from what 



is found in the chloral-hydrate and pyrogallic-acid chart-. 



aring the potassium-sulphide and sodium-sul 

 charts it is seen that in the former th< I aryllis 



