REACTION-INTENSITIES WITH EACH AGENT AND REAGENT. 



161 



Many interesting and unexpected peculiarities will 

 be found upon examination of the foregoing table. For 

 instance, potassium nitrate is inert with the starch of 

 Lilium candid um, 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 case of tannic acid. The sul- 

 phides of potassium and sodium are 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 minutes for the same 

 effect; but the corresponding potassium salts showed a 

 reversal of reaction-intensities. Barium chloride is very 

 active, but barium nitrate is inactive ; and zinc chloride 

 and zinc sulphate show 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 gelatinizatiou, 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 sources 

 by peculiarities of the quantitative and qualitative reac- 

 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- 

 ment of the purposes of the investigation and would lead 

 us far beyond the limitations of space in this memoir, 

 further study of this nature has been omitted. 



VARIABLE RELATIONSHIPS OF THE BEACTION-INTENSI- 

 TIES AS REGARDS SAMENESS, INTERMEDIATENESS, ElC. 



That we are dealing in the starches from different 

 plant sources with stereoisomers, and not merely with 

 mechanical mixtures of varying proportions of several 

 11 



kinds of starch or with starches that differ because of 

 varying impurities, etc., is evidenced by variations ob- 

 served in the reaction-intensity relationships of the 

 parental and hybrid starches with different reagents 

 (see charts of both A and B series). Were there, for 

 instance, merely mechanical mixtures of varying pro- 

 portions representing the parental and hybrid starches, 

 respectively, and a given reagent, it might be found that 

 the reactivities are in the order of seed parent, pollen 

 parent, and hybrid, and that if there were used other 

 concentrations of the same reagent, while the reaction- 

 intensities would be increased or decreased, the order of 

 reactivity would not be changed. Moreover, it would 

 be expected that with all reagents the same order of 

 reactivity woiild be found. It also seems clear, if im- 

 purities played any important part, that when closely 

 related reagents, such as potassium and sodium hydroxide, 

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

 sity might be expected, there should not be a change in 

 the order of reactivity. The opposite is shown by these 

 charts. Thus, Charts A 6, A 7, A 8 (chloral-hydrate, 

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

 ryllis-Brunsvigia-Brunsdonna, reactions show in the 

 chloral-hydrate reactions that the order of reactivity is 

 Briin-sdonna sandera', B. sandcros alba, Amaryllis bella- 

 donna, and Brunsrigia josepliina;, the first two showing 

 a markedly greater reactivity than the second two, and 

 the reactions of the members of each pair being closely 

 alike. In the chromic-acid reactions all four are alike, 

 so that while there is marked differentiation with chloral 

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

 gallic-acid reactions there is somewhat better differen- 

 tiation than in the chloral-hydrate reactions, and also 

 an entire change in the order of reactivities, here the 

 order being Brunsi'igia josephirur, Amaryllis belladonna, 

 Hrnnsdonna sandera; alba, and B. sanderce, the 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. Corresponding 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 

 acid-, which would seem to eliminate the possibility of 

 these changes being due to mechanical mixtures of 

 different starches or to impurities. The Amaryllis 

 set exhibits with potassium hydroxide no noticeable 

 differences in the reactivities of the four starches, because 

 probably of the great rapidity of gelatinization, and little 

 or very little difference is found in the reactions witli the 

 nitric, sulphuric, and hydrochloric acids. But with so- 

 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, moreover, the 

 relationships of order of reaction-intensity are of the 

 most varied character. Thus, in the sodium hydroxide 

 chart the order of reactivity is Amaryllis belladonna, 

 Briinsriffia josrplnnrr, Brunsdonna sandera alba, and 

 B. sanderce, which order is entirely different from what 

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

 Comparing the potassium-sulphide and sodium-sulphide 

 charts it is seen that in the former the order is Amaryllis 



