REACTION-INTENSITIES WITH EACH AGENT AND REAGENT. 



157 



' Mitional comparisons of the data of these 



ii: fact*. 



Tho pota*ium-sul|hidc and sodium-sulphide chart 

 :- in ..-rt.iiu respects ,'-. r rcaem- 

 . .< to tin- hydroxide i h.irt (Chart ll.'U) than to the 

 'iart B 15), and in other respects the re- 

 . thu- in.: hat the alteration of the hydrox- 



ide* into the .-uiphidcs has yielded reagents which give 

 turn* that toggeat the presence of both a> n\< 

 in contradistinction to the reactions 

 of t!i xides and acids which are pre-eminently 



id aninnic. resj>e< lively. These sulphide reae- 

 . in intcn-ity in lioth directions to almost the 

 of tin- abscissa*, from the extremely high 

 * of potassium sulphide that are recorded in 

 /'/fiw, and I'haius in which complete gclatiniza- 

 - in 2 minutes or leas, to the extremely low 

 \ities in //i'/'/>rafrum, llarmanthw. Crinum, etc., 

 tit or leaa is gelatinized in 60 minutes. 

 - of these curves from the acid and base 

 curves are much more marked than the variations of the 

 s themselves, and the quantitative differences ba- 

 the curves tend to be more marked and erratic, 

 and inversions to be more frequent, than in the acid 

 and l>a*<- curves. In \rrine there occurs in the sulphide 

 -. a.s in those of the hydroxide, an inversion, in 

 both charts the potassium salt is the stronger. In In 

 is a marked separation of the curves, as was found 

 to be the case with one exception in the hydroxide reac- 

 : but in three of the starches there was no separa- 

 f the acid curves. In Begonia tocotrana the curves 

 arc loss like those of the bases than of the acids, while 

 in Millonia they stand apart from both base and acid 

 curves. The wide separation of the sulphide curves in 

 Amaryllis is very conspicuous in comparison with the 

 small separation of the base curves and the absence of 

 separation of the acid curves. Similar peculiarities 

 will be found in the reactions of these three pairs of 

 rea?ent. with other starches. 



The potassium-iodide and potaaunm-sulphocyanate 

 ons (Chart B35) bear, on the whole, far closer 

 resemblances to the hydroxide reactions than to the acid 

 or sulphide reactions. In contradistinction to the sul- 

 phides these reagents contain acid radicals that are 

 probably almost inert. Comparing this chart with the 

 base chart (Chart B 33), the most noticeable differences 

 will be found in the reactivities with Amaryllis. Brun*- 

 rigia, Hcemanihus puniceus, Nerine, Irit, Begonia, 

 is, and Mil (onto. Amaryllis and Brunsvigia each 

 exhibits practically no difference in the potassium-iodide 

 or potasflium-sulpnocyanate reactions, but Amaryllis and 

 llrunsrigia are differentiated from each other by both 

 reagent*, both starches reacting more readily with po- 

 tassium iodide than with the other reagent. In Haeman- 

 /'. i/t punier us, while these reagents do not differ in their 

 reactivities, potassium hydroxide yields a markedly dif- 

 ferent result from that of sodium hydroxide. In Nerine 

 reactivity with the iodide is very low and with the sul- 

 phocyanate low; while in the hydroxide reactions those 

 with potassium hydroxide are very high and those 

 with sodium hydroxide very low. In Irit the potas- 

 sium iodide reactions are very much lower in the first 

 three Irids and somewhat lower in the fourth; while 



in the hydroxide reactions in two there are very marked 

 differences, in one no difference, and in another a 

 marked difference, the potassium reactions IM-MI^ the 

 lower when difference exists. In Begonia t 

 and sulphocyanatc reactions show very little difference, in 

 B. tingle crimson tcarlet both reagents acting with greet 

 intensity and in II. socotrana with great slowness, the 

 iodide being practically inert; while in the hydroxide 

 reactions both reagents act with great intensity with 

 B, single crimson tcarlet, potassium hydroxide acts with 

 equal vigor, but sodium hydroxide with low intensity 

 with B. socot ratio. In Phaius and Millonia both the 

 iodide and the sulphocyanate show differences between 

 these genera and between the iiii-nili.-rs of each genus, the 

 iodide U'ing leaa active than the sulphocyanate. While in 

 both I'haius and Millonia marked differences exist be* 

 tween the reaction-intensities of the iodido and the 

 sulphocyanate, there arc comparatively small differences 

 between the intensities of the hydroxides. 



The curve of sodium salicylate (Chart B 36) stands 

 alone, as before stated, and therefore is not comparable, 

 as in the foregoing instances, with that of any other 

 reagent. 



Calcium nitrate and strontium nitrate (Chart B3?) 

 exhibit differences that are most pronounced in Bruns- 

 vigia, Crinum, Nerine, and Miltonia. The calcium curve 

 appears to correspond more particularly with the curves 

 of potassium iodide, potassium sulphocyanate, and so- 

 dium hydroxide; while the strontium curve appears to 

 be more closely related to the curves of uranium nitrate, 

 copper nitrate, cupric chloride, and mercuric chloride. 

 All of the latter curves appear to be very closely related 

 to a common type, which suggests that the reactions, in 

 so far as the latter depend upon the reagents, are due 

 essentially to differences in the basic ions or cations. 



Differentiation of Subgenrric Groups. There is 

 probably no feature of these charts more prominent or of 

 greater value in proof of the worth of the gelatinization 

 method in the differentiation of starches from different 

 sources than the constancy and definiteness in similar 

 and dissimilar directions of the differentiation of sub- 

 jreneric representatives. JIamantnuf l-aihrrin<e and //. 

 punicfUH are, from the standpoint of the systematic, at 

 most well-separated species, but from tho result* of this 

 research they are probably to be regarded as representa- 

 tives of well-defined subgeneric groups. Had thin marked 

 snbgeneric differentiation been indicated by the reac- 

 tions of a single or an occasional reagent it might natur- 

 ally be regarded as being accidental, but it is evident 

 throughout the charts of the reactions of the 21 reagents, 

 except the chloral-hydrate and sodinm-salicylate reac- 

 tions. The one species is as definitely and widely differ- 

 entiated from the other as are genera in general, with 

 the exception only of the closely related Gladiolus and 

 Tritonia. While at the end of 60 minutes there is only 

 slight and questionable differentiation in the chloral- 

 hydrate reactions, and in the sodium-ralicylate reactions 

 no differentiation, there are differences of importance 

 shown during the progress of the reactions (Charts P lOfi 

 and D118). The hardy and tender Crinums are with 

 V.TV reagent markedly differentiated, hut by some to a 

 - degree than by others. The abscisae of the two 

 hardy Crinum.* are in all of the reactions above those 



