REACTION-INTENSITIES \\nil K.\< H AGENT AND REAGENT. 



161 



i. . 



Copprr iiitr.ii- 

 ; ,c chloride. 

 Uofidc 



Z.nr (ulphn 

 Mvcuric chloride 



t'ruitum nilrttr 



i .:.. 



queou* mluUuo. 



l& got*, in 30 c.e. 

 B cm*, in IS e.c. 

 CoBMBtratod... 



18 gnu. in 40 rr. 

 with 10 cm*, 

 of wncDotuum 



:.: .!. 



Stm^inlOe.e 



Do 

 Do 

 Do. 



Do 



Vaifod oooeentra- 



OHSHIMM. 



Do 



Do 



Do 



of (Urea 



M p. et. in 6 min. 

 100 p. et. in IMS lain 



3 min. 



No affect in 00 min. 

 M p. et. in 3 min. 



0H p. et. in 6 min. 

 No ffwt in 60 min. 



Do. 



Do. 



Do. 



Do. 

 Do. 



Do. 

 Do. 

 Do. 

 Do. 



Many interacting and unexpected peculiarities will 

 ind ii|w>n examination of the foregoing table. For 

 initance, potassium nitrate is inert with the starch of 

 ;i candidutn. while potassium nitrite causes com- 

 ^elatiuization in 1 minute; and while the former 

 .on found i" be inactive with this starch, it is re- 

 'th.-r invi -tijrator* as being active in relation 

 starches <>f Tritirum and Xea. This latter pecu- 

 v is noted in the case of tannic acid. Tin- sul- 

 .utsium and sodium an- very active, but 

 :' calcium is inactive. Strontium nitrate 

 i '.i- |* T i cut of the starch in 3 minutes, while 

 . bromide required 30 minutes for tin- name 

 : hut the corresponding potassium salts showed a 

 -dl of reaction-intensities. Barium chloride is very 

 . hut barium nitrate is inactive; and zinc chloride 

 ulphate show the same characteristics. Sodium 

 and hydrochloric acid when in separate solu- 

 ictive, but sodium chloride is inactive, etc. 

 \ detailed study of the specific properties of the ions 

 ml molecules of these reagents in their relations to the 

 starch molecules in the phenomena of gelatinization, and 

 a!-" 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, a* the funda- 

 of these gelatinization experiment* ha.* 

 ntiation of starches from different sources 

 - of the quantitative ami qualitative reuc- 

 : has been attained without reference 

 natures of the chemical reactions involved, 

 and as detailed study of part* played by the different 

 ions and molecules is therefore needless for the fulfil- 

 ment of the purposes of the investigation and would lead 

 iu far U\ :.<! the limitations of space in this memoir, 

 further -tudy of this nature has been omitted. 



V AIM A BLR RKI.ATIOXBHIM OF THR RFACTIOX-IVT 



TIES A8 REGARDS SAME.VRS8, IXTKRH RDIATRXE88, I 



That we are dealing in the starches from different 

 plant sources with stereoisomera, and not merely with 

 mechanical mixtures of varying proportions of several 

 II 



kind* of starch or with starches that differ lcause of 

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

 served in the reaction-intensity relationships of the 

 parental and hybrid starches with different reagent* 

 (see charts of both A and B series). Were there. f<>r 

 instance, merely mechanical mixtures of varying pro- 

 |Mirtn>n> representing the parental and hybrid starches, 

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

 the reactivities are in the order of teed 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 would be found. It also seems clear, if im- 

 purities played any important part, that when closely 

 related reagent*, 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 ,-hown by these 

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

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

 ryllig-HriuuiriyiarHningdonna reactions show in the 

 chloral-hydrate reaction that the order of reactivity is 

 lirnn.fdonna tandenr, B. sandene alba, Amaryllis brlla- 

 ilnnna. and Uruiuriijw jotephina, 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 Brunsrigia josephintr, Amaryllis belladonna, 

 lininsdonna sandera alba, and B. tandem, 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 

 acids, which would seem to eliminate the possibility of 

 these changes being due to mechanical mixtures of 

 different starches or to impurities. The Amaryllis 

 sot exhibits with potassium hydroxide no noticeable 

 differences in the reactivities of the four starches, because 

 probably of the great rapidity of gelatinization, and little 

 r \.-ry little difference is found in the reactions with the 

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

 dium hydroxide and all of the other reagents, excepting 

 chromic acid, one or more of the reactivities will he 

 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, 

 Bmurigia jotfphinfr, Bruntdonna Mndfrtr alba, and 

 B. sandfrte, which order is entirely different from what 

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

 Comparing the potassium-sulphide and nodinm-nulphide 

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



