ASH. 147 
may be very much accelerated when the objects to be examined 
are heated on a channeled piece of platinum-foil in a combustion 
tube in oxygen gas. The same purpose may be attained in a 
more simple manner, though also more slowly, when the sub- 
stance which has been carbonized in a platinum capsule is moist- 
ened with water, again carefully allowed to dry without decant- 
ing the water, and again heated. The water conveys the soluble 
salts to the unoccupied places of the capsule, and the subsequent 
admission of air facilitates combustion. If this procedure is 
repeated several times, a residue free from carbon will in most 
cases be obtained. Too high a temperature has a retarding 
effect when salts, such as phosphates of the alkali metals, are 
present, which fuse together and envelop the carbon; many 
substances are incinerated more completely by a very moderate 
degree of heat than at a higher temperature. Very hard shells 
of seeds offer obstinate resistance to the above procedure of 
moistening, which may be overcome by triturating the carbonized 
substance in the capsule, or in the crucible itself, with the aid 
of a very smooth agate pestle, being careful to avoid loss, and 
afterwards treating with water. By the strong ignition, which 
ordinarily is necessary towards the end, carbonic acid is ex- 
pelled, which must be replaced before the ultimate weighing of 
the ash, in order to obtain figures which will admit of compari- 
son. ‘This purpose is accomplished by moistening the ash with 
a little concentrated solution of ammonium carbonate and 
again drying. It scarcely requires to be mentioned that for 
reduction to ash the substance employed should previously be 
dried at 100° C. 
The addition of ammonium nitrate or ammonium sulphate 
also facilitates combustion, especially with substances rich in 
albumen. : 
The estimation of the residue left upon combustion is of the 
greatest practical value, especially for the examination of vege- 
table powders. For, since every portion of a plant, and thus also 
every drug,. furnishes an amount of ash which fluctuates within 
definite and often quite narrow limits,’ the weight of the same 
‘Thus, by way of example, lycopodium affords 4, pure kamala about 
