382 
ON THERAPEUTICS. 
soluble or insoluble, active or passive, in the organism, ac¬ 
cording- to the nature of the acids and bases of which they 
are composed. However simple and safe the operation of the 
antacids, their exhibition calls for care and consideration. 
1st. It is necessary to determine the presence of acid secre¬ 
tions, as the consequence of disease, because the safety of the 
operation of the antacid is owing in a great measure to the 
presence of an acid that will at once attack it. The conse¬ 
quence of an injudicious use of alkalies in the absence of any 
undue acidity may be readily imagined; the normal acid 
secretions are necessarily modified, and the integrity of the 
blood impaired. 
When the diagnostic symptoms of acidity are obscure, the 
test-paper at once decides the question, and indicates at the 
same time, by the intensity of the reaction, what degree of 
acidity may be present. Acid secretion is so common in 
cases of diarrhoea and mucous irritation that we are in the 
habit of assuming its existence, and dispensing with the 
simple test which would leave no room for doubt, and obviate 
the necessity for speculating upon the medicine best suited to 
the disease. 
2d. The ultimate results of antacid treatment are of im¬ 
mense importance, as far as the selection of the agent is con¬ 
cerned, for the reason already given, viz., the formation of 
salts distinguished by various negative and positive properties. 
The agents mentioned in Morton’s 4 Pharmacy* as antacids 
are carbonates of lime, magnesia, potassa, and soda, and 
soaps. The carbonates of these alkalies are less energetic 
in their action than the alkaline bases alone, and therefore 
are safer, while the weak affinity which combines them to 
their acids renders them equally effective as antacid medicines. 
Excepting the soaps, which are among the mildest ant¬ 
acids, the various drugs are tolerably uniform in their degree 
of alkalinity; but the salts of lime and magnesia are 
insoluble, with few exceptions, while the salts of potassa and 
soda are universally soluble : and consequently, when long- 
continued antacid treatment is necessary, soda or potassa is 
to be preferred to the lime or magnesia, although in the case 
of the latter drug, some purgative salt is frequently formed by 
its union with the acids of the diseased secretion, and thus 
any accumulation of deposit is thereby prevented; but lime- 
salts formed in the system are likely to accumulate if the 
agent be exhibited for any lengthened period, although the 
occasional employment of chalk preparations is not com¬ 
monly productive of mischief. The ordinary chalk mixture 
is a very valuable formula for simple diarrhoea,* magnesia we 
