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of hydrogen, and its physical properties and reactions are the same as adipinic acid. I consider it as such.
None of the other acids afforded by the oxidation of spermaceti have been obtained in a state of sufficient purity to be examined. There is, however, one among them whose copper and zinc salts are more soluble in cold than in warm water, and if a solution of either of them be heated a precipitate is formed, which redissolves upon cooling. This phenomenon is most striking in the zinc-salt. Those portions of the examination of this subject that are as yet incomplete I propose finishing at some future time.
THE CALCARIMETER :
A NEW INSTRUMENT FOR ESTIMATING THE QUANTITY OF CARBONATE OF LIME PRESENT IN CALCAREOUS SUBSTANCES.
Among the most ready methods used for the purpose of estimating the quantity of carbonate of lime contained in calcareous substances are Davy's pneumatic and Rogers's methods, the one estimating it from the bulk of carbonic acid, and the other by the weight of the carbonic acid afforded by the action of an acid. The principal objection to the former is the complication of the apparatus, and for the latter it is necessary to be furnished with a more than ordinary pair of balances, and a set of accurate weights; whereas the instrument about to be described is free from both these objections, with the additional advantage of affording more accurate results.
It appeared at first that by taking a certain quantity of the substance to be examined, and letting fall upon it by degrees a solution of acid, the strength of which we know, that it might be possible to estimate the quantity of carbonate of lime in the same manner as the carbonates of the fixed alkalies are estimated. But for this to succeed it is necessary that the substance should be finely pulverized, and free from any materials soluble in the acid used; but as it is not common to be furnished with these two conditions, another method had to be adopted, the principle of which is to treat the calcareous substance with an excess of acid, the strength of which is known, and then to find out the amount of this excess, thereby knowing the quantity of acid taken up, from which we can easily calculate the quantity of carbonate of lime present. In the application of this principle it will be found that any thing like difficult
manipulation is avoided, and that there is no calculation required.
The first thing to be furnished with is an instrument which consists simply of a tube about half an inch in diameter and ten inches long, having the principal part of it graduated in one hundred parts. The simplest form to be given to this tube is such as is represented in figure 1, the extremity a being drawn out and bent downward, leaving an opening so small as to allow a liquid to flow but slowly from the tube. To the upper part, for convenience' sake, is adapted a perforated cork, with a small tube. This is placed for the purpose of regulating the flow of the fluid, by placing upon it and withdrawing from it the finger, as we may wish to arrest or allow the liquid to flow from the extremity a. With this instrument, that I propose calling the Calcarimeter from its use, we must be furnished with two fluids, a solution of muriatic or nitric acid and a solution of ammonia, both of which are prepared of a certain strength.*
Preparation of the acid solution. This solution is prepared. as follows: weigh out fifty grains of dry, finely-powdered pure carbonate of lime, or what is better, carbonate of lime precipitated from any of its solutions by carbonate of potash or soda. Place this in a cupsule or other convenient vessel; add to it about an ounce of water (this is done simply for the purpose of moderating the action of the acid). Then take the muriatic or nitric acid of commerce, dilute it with one part of water. With this liquid fill the instrument to the 100 point; then let the acid fall gently upon the carbonate of lime, so as not to create a too great effervescence; and by proceeding carefully with the aid of a piece of litmus-paper we can find the exact point at which the carbonate of lime is all taken up by the solution having an acid reaction. When we see that nearly all the lime is taken up we proceed very cautiously, by adding but a few drops of the acid at a time, and agitating the mix
*The capacity of the instrument from 0 to 100 is 30 c. c. m., and the length of the graduation had better be from eight to ten inches. Of course this will vary with the diameter of the tube. As they are all to be of the same capacity, the graduation may be made upon the tube itself, or upon a piece of paper and pasted on, then varnished, first with a solution of gum arabic, and afterward with copal varnish.
ture considerably for the purpose of bringing the insoluble carbonate well in contact with the different parts of the fluid. When the acid reaction commences the acid is no longer added, and the point at which the acid now stands in the tube is marked, and by subtracting that from 100 we have the number of degrees of acid used to dissolve fifty grains of carbonate of lime; but as it is desired that the liquid should be so made as to require 50° of it to dissolve fifty grains of the carbonate, it is diluted with the proper quantity of water. For example, suppose the fluid marked 65° after the experiment; this indicates that 35° of the acid solution were required to dissolve the 50 grains. Now instead of 35° we require it to take 50° to dissolve the same quantity, so that by making up the difference between the thirty-five and fifty with water the solution is prepared; that is to say, to every thirty-five parts of the acid experimented with fifteen parts of water are added. The solution can be again tested if necessary, and slight modifications made.
Preparation of the alkaline solution.-The alkaline solution is now prepared with ease. Let fall 50° of the acid into a vessel, then make a mixture of equal parts of ammonia and water, fill the instrument to the 100°, and let it flow upon the acid, and mark the point at which the acid is neutralized. Suppose it to be twenty, then 80° have been used for that purpose; but it must be so made as that it will require 100°; therefore to every eighty parts of the solution experimented with add twenty parts of In making either of these solutions one gallon. can be made with the same ease as one ounce, and moreover, when they are once made, there is never any necessity of recurring to the carbonate of lime, as the acid may now be prepared with the aid of the ammonia.
Thus then 50° of acid dissolves exactly fifty grains of pure carbonate of lime, and 100° of the ammonia neutralizes fifty of the acid.
As using the same tube for both acid and alkali is attended with some inconvenience, having to wash it out after using one before introducing the other, I have used an additional tube (fig. 2), about the same diameter and a little more than half as long as the calcarimeter, for the acid. It has
simply three marks upon it. The capacity of the tube from the point marked a to the lower extremity is equal to the capacity of 50° of the other tube, and the other two marks correspond to ten and five. The use that is made of these will be hereafter explained.
Manner of performing the analysis.-Being furnished with the two tubes, the two fluids, a capsule 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 substance to be examined, place it in the capsule, 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 holding 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 toward 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 substance, arresting at will the progress of the flow by simply placing the finger upon the tube in the cork. This instrument should always be transferred to the left hand and held in an inclined 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 as 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 percentage of carbonate of lime contained in the calcareous substance examined. We may be saved the trouble of testing
*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.