ON DIGrlTALIC ACID AND THE DIGIT ALATES. 183 
action of alkaline bodies 5 thus in preparing it. excess of ba- 
rytes must be avoided. 
Digitalic acid has a sour but not disagreeable taste ; it 
immediately reddens litmus paper, expels carbonic acid from 
carbonates, and forms digitalates, and combines directly with 
basic oxides, and the soluble salts which it forms become 
readily yellow in the air. 
M. Morin states the properties of the following digitalates: 
Digit alate of Soda. — Obtained by exactly saturating the 
acid with carbonate of soda, and evaporating the solution 
under the air-pump vacuum. It is white, and crystallizes 
very well, but by exposure to the air it becomes quickly 
yellow, and so also does the solution. It is very soluble in 
water. 
Digitalate of Potash. — Obtained by decomposing the 
carbonate in the same way as the preceding. It crystallizes 
with difficulty and is very soluble in water. 
Digitatate of Mag7iesia.~-Obt3.med from the acid and 
carbonate of magnesia ; soluble in water. 
Digitalate of Barytes. — Obtained by saturating the acid 
either with barytes or the carbonate. It is soluble in water 
but insoluble in alcohol and in aether. Quite colourless, but 
by exposure to air and heat it becomes brown. 
Digitalate of Lime is obtained in the same way as the 
barytic salt, with which it has great analogy ; being insolu- 
ble in alcohol and in aether, it may be employed for the pre- 
paration of digitalic acid. 
Digitalate of Zinc. — Obtained by treating the carbonate 
with digitalic acid ; the filtered solution is to be evaporated 
by the air-pump vacuum. 
This salt is formed notwithstanding an excess of carbonate. 
It is obtained at first as a transparent salt, having the appear- 
ance of a thick solution of gum ; but after some days a num- 
ber of small arborescent crystals are formed. This salt does 
not so quickly become yellow by exposure to the air as those 
previously described. 
