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or weasel, they always cry out when the enemy gets within two or three yards of them, and are generally so terrified that they lie down and are caught; therefore the cry in this case is evidently from fear.

I one day disturbed a rabbit which ran away in so singular a manner that I followed it, and saw that the flesh had been eaten away from the back of the head to the top of the shoulders; the sight was so sickening, that I turned away, thinking the poor creature could not live many minutes. About two hours afterwards, I went with a view to pick up and examine the rabbit, and when I came to the spot, was surprised to see it jump up and run away as before; the person who was with me ran after it, the rabbit ran into a bush and he caught it. Now, although the poor thing was so injured, there was no cry when I first disturbed and ran after it, or when it was disturbed and followed the second time, but the moment it was caught it began to cry out, showing that fear could excite a cry which all its sufferings could not do.

When rabbits are caught in traps, if not taken out in a short time they are almost sure to escape, either by breaking away by force from the trap, and tearing off the leg, or by biting the leg off. These traps are made to clasp very strongly, but to prevent escape as far as possible, they are made purposely not to close nearer than about the eighth of an inch, and the teeth are rounded so as not to cut; but rabbits are so indifferent to pain that I have seen their legs left in traps with the sinews attached to them, just as the sinews are drawn from the fowl's legs previous to cooking, and yet although the bone is so broken, and the muscles and sinews torn apart in this manner, it seems to have little or no effect on the health of the animal.

I have seen them caught after having recently lost a leg, and to all appearance, in as good health, and as fat, as if nothing had happened to them. A short time since, I saw a rabbit caught which had but one leg, having lost one hind-leg apparently some time, and the two fore-legs very recently, but although the poor animal had been obliged to go along as it could with its one leg and the bare stumps of the others, it was in good condition and healthy.

Rats will bite off their legs in a similar way, and escape; but I do not know of any animal which is strictly a beast of prey, or rather a hunting animal, that will do so. I have never known a cat, polecat, or such animals do it, although they may sometimes lose a leg in a common trap which shuts close and is apt to cut; and I have lately known a fox found in a wood in a dying state, from starvation, with a trap on its leg, an incumbrance that a rabbit would have been free from in a very short time.

These facts, will, I believe, bear me out on the point, that the sense of pain is for the preservation of animals, by compelling

them to take due care of themselves, and that no animal has a greater share of the sense of pain than is necessary for the preservation of the class to which it belongs. The loss of a leg must be a great inconvenience to any quadruped, but rabbits or rats may still procure food without it; even the case before alluded to of the hyena, does not tell against it, as the hyena does not get its food by swiftness of foot alone, nor is its foot the weapon of attack, as with the cat tribe; but if a fox, wild-cat, polecat, or any animal of that description, loses its leg, it is a great chance if it does not die of starvation, unless its prey be very plentiful; tberefore, as the legs are of so much importance to these animals, they seem to be endowed with a sense of pain in proportion to their usefulness, as a guard for their preservation.

From the ease and indifference with which crabs and lobsters will throw off their claws, when under the influence of sudden fright, or when their claws are injured, it is evident that their sense of pain from mutilation must be very little ; and, according to the argument I have advanced, it may be asked, of what use can the sense of pain be to any of the crustaceous tribes? They are coated in armor sufficient to protect them from all minor enemies, and if they get into the power of an enemy strong enough to crush through their shells, of what use can the sense of pain be to them then? But they shew signs of great pain when thrown into boiling water, and I see no reason why they may not be insensible to pain from mutilations, and yet be sensible, in a high degree, to pain from extreme changes of temperature; for, as there are no bounds to prevent their ranging over all parts of the sea, it is probable that a sense of temperature is necessary to them, and many other animals also, to keep them to those parts of the world which they are formed to inhabit. It may also be useful to keep them to those parts and depths in the sea that are necessary for their young to arrive at maturity.

From the observation of Sir Humphry Davy, and others well acquainted with the habits of fish, it is very probable that the sense of pain in many of them is very trifling; and when we consider the fecundity of the cod, and many other fishes, the number of eggs deposited by a single cod-fish in one season (according to Leuenhæck, upwards of nine millions), and bear in mind, that unless these fish more than double their numbers annually, that of the myriads of fishes that are hatched from these eggs, not more than three or four, on an average, can arrive at the same maturity as the parent fish, the others being all destroyed at different stages of their growth, being the food of other animals; it does seem probable that there is a similar dispensation of mercy to them, as I have endeavored to shew there is to rabbits and hares.

Many cases may be brought forward to shew the absence of pain in insects. I have seen a wasp eat a fly almost immediately after a portion of its own abdomen had been cut off ; I have also seen a cockchafer crawling and eating on a hedge after its abdomen had been emptied of the viscera, probably by some bird. It is well known that a dragon-fly will eat freely for a considerable time while confined by a pin through its body; and every one who has collected entomological specimens, must know the difficulty in killing some of the larger moths. But as this paper is already much longer than I originally intended, I shall say no more on this point, as the remarks on the subject in the introduction to Kirby and Spence's Entomology are very generally known.

It may be well to reflect for a moment on the constant slaughter that is going on among the lower class of animals. The number of flies eaten by a single pair of swallows and their young must be immense.

I once observed a rather extraordinary illustration of the law of nature to eat and be eaten. I kept in a glass globe a variety of the smaller aquatic animals, such as the larvæ of the dragonfly, &c., and one day introduced among them a few of the common water newts and water beetles, one of which was the Dytiscus marginalis. The dragon-flies had been living upon the animalculæ, &c., the newts attacked and devoured the dragon-flies. The next morning I found one of the newts lying at the bottom of the vessel half-eaten, and, while looking on, saw the ditiscus attack another newt. Not wishing to have them all destroyed, I took the ditiscus out of the water, and put it in the sunshine a few minutes, when it flew away, and had not gone more than thirty or forty yards when a sparrow flew after and caught it. This constant destruction of life would be fearful to contemplate, if there is truth in the quotation so often made, that “the poor bectle that we tread upon, in corporal sufferance finds a pang as great as when a giant dies." April 19, 1847.

Art. X.- On the Absorption of Carbonic Acid Gas by Liquids ;

by Prof. W. B. Rogers, and Prof. R. E. Rogers, University of Virginia.

Since the experiments of Dalton and Henry of Manchester, and the more elaborate researches of Saussure on the absorption of carbonic acid and other gases by various liquids and solids, this branch of enquiry seems to have been regarded by chemists as in a great degree exhausted, and unlike most of the researches of that earlier day, has failed to command any extensive reinvestigation.

The experiments forming the subject of the present paper, extend over a part only of the ground occupied by those of Saussure, but although confined to the absorption of carbonic acid, they embrace many liquids not referred to in his enquiries, or in the similar but less varied observations of Dr. Henry. We believe that they furnish much more accurate results than the simple but rather rude methods used by these experimenters could be expected to afford. Besides a great number of results obtained with different liquids and solutions at 60°, they include in the case of water a series of determinations at various stages of temperature, from 320 to 100°.

Apart from the general value which in a scientific sense must always attach to the determination of exact numerical constants in subjects of this kind, there are points of the present enquiry which claim attention from their bearing upon certain other branches of research. It will be seen, for example, in the sequel, that the absorption of carbonic acid gas by sulphuric acid at ordinary temperatures, is far greater than chemists have hitherto suspected, and that the processes in which this gas, before being estimated, is made to pass through or over a considerable volume of sulphuric acid, may lead to errors which although hitherto unnoticed, are too important to be overlooked.

In a paper, on the analysis of the carbonates, published in the American Journal of Science in 1844, we called attention to the fact, that in using sulphuric or hydrochloric acid for decomposing the carbonates, the resulting solution or mixture always retains an amount of carbonic acid too great to be neglected in accurate research, and that this gas cannot be expelled without the use of a continued boiling heat. Some experiments undertaken in the hope of ascertaining precisely the absorbent power of these acids and solutions, led us into the more extensive field of enquiry, of which we propose now to embody the results.

Availing ourselves, at first, of the simple methods employed by Dalton, Henry and Saussure, we found that with all care in the manipulation and in applying the proper corrections, we were unable to attain consistent and reliable results.

In operating with a graduated tube over mercury, as was practised by Dalton, and by Saussure for the more absorbent liquids, the great slowness of the absorption in many cases, rendered it impossible to determine, even after some days, whether the action was still in progress or had ceased, and the form of the apparatus made it unsafe and almost impracticable to apply that brisk and continued agitation, which is the only means of greatly expediting the absorption. With some liquids, such as sulphuric acid, the penetration of the gas is so extremely slow, that without this mechanical aid, weeks of exposure would probably be necessary to complete the absorption. Yet by continued and thorough

Second SERIES, Vol. VI, No. 16.-July, 1848.

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shaking for thirty minutes, this result is attained so perfectly, that no prolonged exposure afterwards indicates a continuance of the absorption. The importance of attending to this point in constructing an apparatus for experiments in absorption, is evident from the fact that while by our observation, which occupied generally less than thirty minutes, sulphuric acid of common density was found to absorb 98 per cent. of its volume of the gas, Saussure's experiments, which continued for one or more days, make the absorption only 45 per cent.

The difficulty and uncertainty of the method above mentioned, is moreover increased by the necessity of restoring the instrument to the standard temperature before measuring the absorption, and of taking account of the change of barometric pressure in the interval. To these objections must be added the errors of measurement due to the weight of the column of liquid above the mercury, as well as the large diameter of the tube in which it was necessary to operate, and lastly, the consideration that this method is inadmissible where we are operating with liquids, which like nitric acid and many saline solutions react with mercury.

Results as little satisfactory attended our trials with the other * process of Saussure. In this mode of operating, which he adopted in cases where the absorption was small, the liquid and gas are brought together in a well stopped bottle, and after continued agitation for some time, the absorption is measured by removing the stopper in an immersed position. But here, besides the difficulty of making the absorption in a precise manner, we encounter a more serious objection in the fact, that the rarefaction of the remaining gas causes the absorption to cease before reaching the full amount proper to an undiminished pressure. This evil may, it is true, be rendered insignificant in cases where the absorption is slight, by using as Saussure did, a volume of gas many times greater than that of the liquid; but with carbonic acid, such a procedure would in most cases call for so large a volume of gas as greatly to increase the errors arising from a slight variation of temperature during the experiment, while it would augment the difficulty of securing the coincidence of temperature required.

In the syphon formed apparatus used by Dr. Henry, the flexible tube beneath, facilitates the experiment by enabling the operator to apply agitation to the wider limb containing the gas and liquid, but the results are exposed to error from the dilation of the flexible connection and from the effects of concussive compression caused by shaking a large mass of mercury with the gas and absorbent liquid. Of course, this method is inapplicable where the liquid reacts upon the mercury

From what has now been stated, it will we think be apparent that the modes of experimenting on this subject, used by the dis

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