§§ 547 — 549 *] digitalis group. 443 
On hydrolysing with alcoholic soda, digitoxin breaks up into digi- 
toxegenin, C 22 H 31 0 4 H, and digitoxose, C 9 H 18 0 6 , thus :— 
^ 31 -^- 50^10 — C'qHt 8 O fi + C 99 H 32 0 4 . 
9 18 
22 XA 32 vy 4’ 
§ 547. Digitaleretin, a decomposition product of digitalin, is a yellowish-white 
amorphous powder, possessing no bitter taste, melting at 60°, soluble in ether or in 
alcohol, but insoluble in water. 
Paradigitaletin is very similar to the above, but it melts at 100 °, and is insoluble 
in ether. 
§ 548. Several other derivatives have been obtained and described, 
such as the inert digitin, digitalacrin , digitalein, and others, but their 
properties are, as yet, insufficiently studied. 
§ 549. Reactions of the Digitalins. —0'01 grm. of digitonin dissolved 
in 5 c.c. of HC1 (sp. gr. 1-19) and heated on the water-bath gives a 
liquid, at first yellow, then deep red, and finally dark blue. This reaction 
thus serves to distinguish digitonin from the three other constituents, as 
well as from saponin ; but digitalin gives somewhat similar reactions. 
Sulphuric and gallic acids colour the glucosides of digitalin, digitalein, 
and digitonin red, but not digitoxin, which can be identified in this way. 
Sulphuric acid and bromine give with digitalin a red, and with digi¬ 
talein a violet coloration, which, on the addition of water, change respect¬ 
ively into emerald and light green. This, the most important chemical 
test we possess, is sometimes called Grandeau s test ; it is not of great 
delicacy, the limit being about 0-1 mgrm. 
Digitoxin does not liberate iodine from a mixture of sodium iodate 
and sulphuric acid. If pure, it is not coloured red by bromine water. 
Triturated with ammonium molybdate or potassium dichromate and 
water, or glacial acetic acid and sulphuric acid added and warmed, 
molybdate produces azure-blue, dichromate green colours (C. Reichard, 
Pharm. Zentr ., 1913). 
It is not easy to identify with certainty the digitalins from an 
alcoholic extract of animal tissues, and any indications must be con¬ 
firmed by physiological tests ; because the reactions are almost bound to 
be made on substances which are not pure, and such reactions are mainly 
colour reactions, which as a class are unsatisfactory. 
The digitalis glucosides can be in part shaken out of an aqueous acid 
solution by chloroform. The acid solution from the presence of digit- 
saponin froths on shaking. On boiling the acid solution saponification 
occurs, the solution no more foams, but reduces Fehling’s solution. This 
of course only shows the presence of a glucoside. 
If the chloroform extract is dissolved in a little acetic acid containing 
a trace of iron salt, and treated with Kiliani’s reagent, as detailed p. 441, 
a ring of a bluish or violet colour gradually appears, and later the acetic 
acid itself becomes bluish ; but similar colours are produced by brucine, 
veratrine, and quino-tannic acid. 
