99 



The alkaloid thus far most thoroughly examined is cocain. Crystalline deposits 

 have been obtained with each of the following eleven reagents, viz, palladous chlorid, 

 platinum chlorid, gold chlorid, picric acid, chromic acid and hydrochloric acid' 

 potassium dichroiiiate and hydrochloric acid, potassium permanganate, potassium 

 chromate, sodium carbonate, ferric chlorid, and potassium hydrate or sodium hydrate; 

 noncr\>tallim- deposits were obtained with chlorzinc iodid, picralonic acid, Mayer's 

 reagent, phosphomolybdic acid, phosphotungstic acid, Kraut's reagent, Wagner's 

 it, barium mercuric iodid, and potassium cyanid. 



The following observations were noted concerning the various reactions with cocain 

 iii which crystals were produced: 



full minus chlorid. This ia one of the most characteristic tests for cocain though 

 in.t quite M -ensitive as u'old chlorid. The crystals vary in form greatly, according 

 to tin- conditions of precipitation. There is at first formed, except in very dilute 

 solutions ( 1 :3<M) and up), an orange-colored amorphous-like or oily precipitate from 

 which, on standing, crystalline forms of golden brown color are produced. One of 

 the most ( '0111111011 forms i> that obtained with a 1:100 dilution, when feathery crystals 

 are formed which have a mdencyto twin. With a solution of 1:20 a dense 



precipitate i- thrown down, out of which hexagonal plates are at first formed and fre- 

 (juently followed later by sheaf-like clusters of fine-pointed acicular crystals. A 

 dilution greater than 1:500 gives crystals only with difficulty, crystallization being 

 induced by rubbini: the >lide with the glass stirring rod. The limit of the test is 

 0.2 ' 



/'/'" '"rid. With a 1:20 solution a dense white precipitate is formed and 



quickly followed by the production of very narrow feathery crystals many times 



twinned so as to resemble a bird with outspread wings. Clusters of more than two 



umlaut. If the reagents are mixed slowly the crystals are more like those 



dilution. With a 1:100 dilution the feather type is much more prominent, 



the secondary i l.ein- well developed into frost-like forms. With 1:1,000 



Dilutions either .-h-.rt thick crystals are formed or else plate crystals twinning in a 



manner are produced. The dilution limit is about 1:4,000, and 



the limit in 1 : 1 ,000 is 0.2 ^gr. 



/ i-lilnr'nl. This is the most sensitive reagent for cocain so far found. At 1:100 



feail ke crystals are produced, together with some nearly smooth star-like 



aggregates. At 1:1,000 the form is much the same, but the branches usually bear a 



i outline. iMamond plates are also roduced. At 1:4,000 a cross-like form 



predoniinaii--. i h< n >ss-bar beiiiir short. A few rosette crystals frequently are present. 

 .1- can be . I Mined in dilution up to 1:20,000 and the limit of the test for dilu- 



ut I::UMM) is 0.033 //gr. 



tic acid.- Tin- i- a good reagent for dilutions up to 1:800, though the crystals 



produced are n.,i very characteristic for this alkaloid. They are produced in spherical 



<f tine lemon-yellow acictilar forms. The reaction takes place 



quickly, and no dillicuh rienced in producing them nearly to the limit of 



dilution. At 1 ::;m the limit i.- O.L' //i;r. 



ni irmnnganate. With cocain, solutions up to a dilution of 1:700 give 

 purple --o|,,red .square plates, or aggregates of this form. Vigorous rubbing of the 

 slide is often necenar] to -tart the crystallization, which then proceeds readily. 

 When they b. -in to cry.-tallize spontaneously, the plates are sometimes deposited in 

 spherical aggregates. The limit at 1:400 is 2 //gr. 



Chromic nriil ami hydrochloric acid. This test is made by adding a small drop of 5 

 per r.-nt chromic acid solution to the test drop. A precipitate is formed which on 

 stirring di-app. -ar- if too much has not been added). A small drop of strong hydro- 

 chloric aid is added and a yellowish deposit is produced, which after rubbing of the 

 slide should in a few moments be transformed into loose spherical clusters of an acicular 

 crystal. This test appears to be one of the most uncertain because of the difficulty 

 with which the ery.-talli/atioiiis sometimes induced to begin in dilutions greater than 

 A concentration of 1:1,000 has produced positive results on standing several 

 minute.-,. The limit appears to be for 1:100 about 3 //gr. 



/'... hromale and hydrochloric add. This test gives the same form of crystals 



as the chromic acid and the test is conducted in a similar manner. The limit of 

 dilution is about 1 I. (MM) while at 1 :100 the limit is 3 Agr. 



Ferric rhlnrid.- The crystals are spherical aggregates of rather coarse blade-like 

 Is with chisel-shaped ends. The limit of dilution is about 1:1,000 and in a 

 dilution ,,f l; KMI the limit is li //gr. 



/'"tnsifium hydrate, or sodium hydrate. This produces a white amorphous precipitate 

 which changes into crystals on standing or by rubbing the slide with a glass rod. 



