47° 



THE TROPICAL AGRICULTURIST. [December i, 1884. 



Calculated. Found. 



HjO .... 431 . . 423 

 The tartrate dried at 120 ° C. takes up from moist air 

 only 1 molecule of H. 2 ; it has then the same percentage 

 composition as neutral tartrate of quinine. 



This dissimilar composition of the two tartrates must 

 not be overlooked in the estimation of quinine optically 

 by the method of Oudemans, jun,* otherwise, up to about 

 4 per cent of ciuchonidine sulphate might be "found" in 

 a quinine sulphate obtained from cuprea bark in which 

 not a trace was present. This mistake may, however, be 

 easily avoided, by previously determining the amount of 

 water in the tartrate, and as I have done in my optical 

 quinine test.f starting from the anhydrous salt. 

 77/. — Conversion of Homoquinine into Quinine. 

 Some observations which I niade during the investigation 

 of cuprea bark agreed pretty well with the presumption 

 that under certain conditions homoquinine might change 

 into quinine. To ascertain these conditions I first heated 

 the alkaloid to 100 ° C. with dilute hydrochloric or sulphuric 

 acid, sometimes in open vessels and sometimes in closed 

 tubes, but without result. Hydrochloric acid of specific 

 gravity 1"126 acted no better; but upon heating the latter 

 solution some hours to 140 ° C, methyl chloride and 

 apoquinine were formed, as with quinine. Nevertheless, 

 I was unable to separate quinine from this solution by 

 means of ammonia before this formation took place. If, 

 however, soda ley were used for the precipitation of the 

 alkaloid, a certain quantity of quinine now resulted. In 

 consequence of this observation I was now able, by repented 

 precipitations with soda ley. shaking the precipitates with 

 ether, and this solution with very dilute sulphuric acid, to 

 convert homoquinine completely into quinine. Thecnnversion 

 is essentially accelerated by heating the base with soda 

 ley, a previous heating of the acid solution being thereby 

 made unnecessary. 



From the quinine obtained through conversion of homo- 

 quinine the neutral sulphate was prepared, which gave — 

 I. 0-5425 gram at 120° 0'08!W II. ,0. 

 II. 0-7320 gram at 103 ° 0-1170 H,0. 

 III. 0-4025 gram at 120 ° 00720 H 2 0. 

 Calculated for Found 



(C, H 21 N.,0 2 )„S0 4 H, + 8H.,0 I. II. III. 



H,,<>; . . . 16-17 " 16-46 1505 15-54 



This salt effloresced rapidly in dry air and then contained 

 still 2 molecules of H^O. On the other hand, tie' dried 

 sulphate quickly took up 4 to 46 per cent of water. 



In other respects also, no difference could be recognized 

 from the known pure sulphate. 



//". — Concluding Remarks. 



The foregoing results justify the conclusion that llarret 

 and Wood in their investigation converted the homoquinine 

 into* quinine and that it thus escaped observation by them. 

 I myself also had previously fruitlessly endeavoured to 

 prepare the alkaloid in question from cuprea bark. It was 

 only after a series of English chemists had simultaneously 

 affirmed the existence of homoquinine that 1 felt 1 ought 

 to drop my doubts as to the peculiarity of the alkaloid, 

 which was at any rate first prepared by Tod ; but up to 

 that time I had considered the substance in question to 

 be none other than crystallized quinine. 



Upon the grounds stated my original opinion as to the 

 nature of this substance might still be correct. It is true 

 that at present I have not yet succeeded in preparing 

 homoquinine from cinchona bark, and it may be there is 

 no present prospect that it is obtainable from that bark, 

 so that this substance may still pass as characteristic of 

 the Hemijia ped iuicvl lata, which yields the cuprea bark, 

 lint I might maintain to the contrary that I formerly 

 had the opportunity of being able to point out that quinine 

 under certain conditions would become modified, in that 

 it passed into the anhydride, and that this substance also 

 behaved as a specie/? alkaloid. At that time also I succeeded 

 in reconverting this substance into ordinary quinine through 

 prolonged treatment with dilute sulphuric acid, though not 

 through precipitation with soda lye.J 

 Besides this modification of quinine there exists at least 



* Annalen, clxxxii., 65. 

 t Annalen, ccv., 217. 

 | Annalen. clxxvi., 207. 



one more, which forms with sulphuric acid a neutral sulphate 

 that separates from a hot aqueous solution as a jelly, only 

 subsequently assuming the crystalline form* I was formerly 

 inclined to place this peculiarity of the sulphate iu question 

 to the account of a colouring substance, concerning which 

 not much was known. Nevertheless, exactly those solutions 

 from which quinine sulphate separates at first in a gelatinous 

 form are so little coloured that the cause of the gelatiuization 

 might far rather be sought in the absence of colouring 

 matter. I may also add that in the cases mentioned, if the 

 alkaloid be taken up in ether, the ethereal solution gelatinizes 

 relatively easily. These peculiarities of the alkaloid dis- 

 appear, however, most surely if the sulphuric acid solution 

 be subjected to a prolonged boiling. 



The most important results of the foregoing investigations 

 may be brought together in the following propositions:— 



(1.) Homoquinine is a modification of quinine. 



(2.) Cuprea bark in many cases contains this modific- 

 ation together with quinine. 



(3.) Several modifications of quinine exist, which by 

 suitable treatment pass into ordinary quinine.— Pharma- 

 ceutical Journal. 



WOODS AND KAINFALL. 

 The fact that a spring is often seen to increase in vol- 

 ume during the period in which a wood is growing, and 

 ceasing to flow on the same being cut down, at the same 

 time that the soil, when it is covered with trees, is usually 

 in a dry state, has frequently been mooted, and a variety 

 (.1 reasons adduced for this peculiar feature. I therefore 

 venture to note down my own observations, taken in various 

 parts. Surface-soil will be dry owing to the root absorb- 

 ing as much water or nearly as it can hold between its 

 organic particles. What cannot be retained by the soil 

 nor be utilised by the roots during its downward progress 

 reaches lower and impervious strata, and will there remain 

 to form springs may be, or it may rise to a higher level 

 by natural increase from snow and rain, and then flow 

 over through pervious strata to lower levels such as those 

 of brooks and rivers. 



On bare land, although there is nothing iu the way of 

 roots to absorb moisture, if we except the roots of herb- 

 age, the surface-water runs on to lower levels, if the surface 

 is hard, or forms pools and marshy places, and in stiff 

 soils remains for lengthened periods, during those periods 

 of the year when the sun has but little evaporating effect 

 on water. In the hotter months the evaporation from bare 

 land is much greater than is possible in a wood, the soil 

 of which is shaded by the trees, and therefore rains fall- 

 ing at that period have not time to soak into the land, 

 but are rapidly evaporated by the sun-heat, and carried' 

 elsewhere in the form of vapour. Perhaps bare, light soils 

 overlying gravel or greensand, lose less by evaporation than 

 the former, as the descent of rain is" much quicker to 

 depths beyond the reach of the sun's power. 



Where forests abound floods are much rarer in the main 

 streams, provided the banks are sufficiently high and strong, 

 and that there is care taken that no silting up occurs' 

 from any cause, thereby raising the bottom of the stream 

 in places, and so causing a want of room for large quant- 

 ities of water. Where snow remains on hill tops, and then 

 suddenly melts in June and July, floods are then the most 

 difficult to avoid, or to control, although forests may clothe 

 the lower portions of the hills and line the streams. liut 

 if such hills— when the altitude admits of its being done 

 —were planted to their tops, the greatest risk would be 

 averted, as the melting of the snow would be gradual, and 

 the consequent rush of water after heavy summer down- 

 falls would also be much less rapid. Forest ground evaporates 

 therefore less than bare ground, and the trees on it consume 

 much water by their roots and absorb also a little by their 

 leaves in summer time. In winter the action of trees on 

 the water falling on the land becomes more controlled by 

 the nature of the soil, its slope, and the composition of 

 the _ underlying strata. Trees at that season exert the 

 minimum of direct influence through root action, and water 

 either sinks slowly, as in heavy soils and iu partially previous 

 strata, or rapidly in those of an opposite nature,'and much 

 finds its way by artificial and natural channels to rivers, 



* Annalen, clxvi,, 262. 



