Carbonate of Lime present in Calcareous Substances. 265 
Manner of performing the analysis.—Being furnished with 
the two tubes, the two fluids, a cup or other convenient vessel, 
a small piece of glass rod a few inches long, a wine-glass, and a 
piece of litmus paper, a portion of which has been reddened by an 
acid, we proceed as follows. Weigh out fifty grains of the sub- 
stance to be examined, place it in the cup and add to it about 
one ounce of water, fill the instrument last described up to-the 
highest mark upon the stem with the acid; this is done by hold- 
ing it between the thumb and fore-finger, having the little finger 
applied to the lower opening. After the acid is poured in, before 
withdrawing the finger, introduce the cork and place the fore- 
finger of the other hand upon the opening of the tube on the 
cork, for the purpose of preventing the liquid flowing out, when 
the lower opening is left unprotected ; after seeing that the acid 
stands exactly at the mark, it is allowed to flow gradually upon 
the substance. After all the action has ceased, stirring it towards 
the end to insure this result, we fill the graduated tube with the 
solution of ammonia, in the same manner as we did the last, and 
let it fall gradually upon the mixture of acid and calcareous sub- 
stance, arresting at will the progress of the flow, by simply pla- 
cing the finger upon the tube in the cork. This instrument 
should always be transferred to the left hand and held in an in- 
clined position. During the addition of ammonia, the mixture 
should be well agitated with the glass rod, and occasionally tested 
by bringing a little of it upon the extremity of the rod in contact 
with the litmus paper, and so soon as it ceases to turn this paper 
red, or begins to. turn the red part of it blue, the experiment is 
completed, and we now look at what number of degrees the fluid 
stands in the tube and we are furnished with the per centage of 
carbonate of lime contained in the calcareous substance examin- 
ed.* We may be saved the trouble of testing too often, by pay- 
ing attention te the strength of the reaction of the fluid upon the 
litmus paper. 
In most marls which have served as the subjects of my exper- 
iments, more or less alumina is to be found, a part of which is 
dissolved by the acid, of which part a very good use can be 
made. While adding the ammonia, the alumina immediately 
* If magnesia happens to be present, it will be estimated as lime, but this will 
very seldom be a cause of error, as it exists very rarely in calcareous manures, for 
which this instrument is particularly intended. 
Vol. xiv, No. 2.—July-Sept. 1843. 34 
