Part 36

Not to give rise to valerianic acid under the action of hydrated potassa.

The following table shows the amount of vapour of amylene in air which is saturated with it at various temperatures. The specimen of amylene with which I made the experiments began to boil at 95° Fah.

Temp. Fah. Vapour. Air. 24° 20·3 79·7 26 20·9 79·1 28 21·6 78·4 30 22·3 77·7 32 23·2 76·8 34 24·3 75·7 36 25·5 74·5 38 26·8 73·2 40 28·2 71·8 42 29·6 70·4 44 31·1 68·9 46 32·7 67·3 48 34·3 65·7 50 36·0 64·0 51 36·9 63·1 53 38·6 61·4 55 40·0 60·0 57 42·5 57·5 58 43·7 56·3 59 45·0 55·0 60 46·5 53·5 61 47·7 52·3 63 50·4 49·6 65 53·1 46·9 67 55·9 44·1 69 58·8 41·2 71 61·9 38·1 73 65·1 34·9 75 68·6 31·4

I was not aware of the existence of amylene till 1856, or I should have tried it sooner; for I made inquiry in 1848 for a substance named eupion by Reichenbach, its discoverer, but was unable to obtain it. Eupion is a carbo-hydrogen, described as having all the physical characters which belong to amylene, though obtained in a different way; and I believe it is the same substance, or the hydride of amyle. Reichenbach obtained it from coal tar, but other chemists have not been able to make it.

Judging from experiments which I had made on analogous substances, there could be no doubt of amylene causing insensibility when inhaled; but I could not tell, without actual trial, whether it might not be unpleasant in its action.

I believe that amylene had but rarely been made, and only in very small quantity, until I requested Mr. Bullock to make it for me. For some time afterwards, soon after my first paper had appeared on the subject, M. Berthé, of Paris, made some amylene and submitted it to M. Balard, its discoverer, who acknowledged its purity, and was astonished at the great quantity M. Berthé had obtained. This quantity, however, appears to have only been forty grammes, or about ten fluid drachms.

As soon as Mr. Bullock succeeded in making some amylene for me, I proceeded to perform some experiments with it on small animals. I found that it was necessary that an animal should breathe air containing about 10 per cent. of the vapour in order to lose its consciousness, and that 20 per cent. caused a deep state of insensibility, whilst 25 per cent. could be breathed with perfect safety.

The following are a few of the experiments.

Experiment 43. A guinea pig was placed in a glass jar holding four hundred and twenty-eight cubic inches. Fifteen grains of amylene were dropped through a small tube in the air-tight cover of the jar, fell upon blotting paper suspended within, and quickly evaporated and became mixed with the air. In three or four minutes the guinea pig staggered and became altered in its manner. It did not become further affected, although it was allowed to remain for ten minutes. When taken out its sensibility did not seem impaired. Each grain of amylene produces 1·315 cubic inch of vapour, and consequently the air in this experiment contained 4·6 per cent. of vapour.

Experiment 44. The same guinea pig was placed in the same jar three days afterwards, and twenty-five grains of amylene were introduced in the same manner. At the end of two or three minutes the guinea pig seemed estranged in its manner, and turned its head from side to side. In a little time it seemed getting drowsy, but at the end of twelve minutes it was still on its legs and moving voluntarily. Eleven grains more of amylene were now introduced. In a little time it sank down unable to stand, and on being turned over by inclining the jar it made efforts to right itself, which became more and more feeble. It was taken out at the end of fifteen minutes, i. e., three minutes after the introduction of the additional amylene. It gave a slight squeak, and moved its feet and eyelids on being lifted. On being pricked it gave decided evidence of sensation. It recovered in a few minutes. There were 7·7 cubic inches of vapour in each one hundred cubic inches of air in the first part of the experiment, and eleven cubic inches in the latter part.

Experiment 45. Six fluid drachms of amylene in a little bottle were put into a glass jar of the capacity of one thousand six hundred cubic inches, and the mouth of the jar was tied over with a large piece of oiled silk. The bottle was emptied by inclining the jar, and the amylene was made to run about the sides of the jar till it had all evaporated. A guinea pig was then folded in the superabundant oiled silk beyond the string which tied it, the string was then opened, and the animal introduced into the jar without allowing any communication with the external air. The guinea pig began to be affected within half a minute, and in a minute it was lying insensible, but moved its limbs when it was rolled about in the jar. In two minutes it was flaccid, and could be rolled about without causing any resistance or muscular action. It lay relaxed and motionless till taken out at the end of four minutes, although by an occasional motion of the eyelids it seemed not altogether insensible. It was quickly taken out, but the moment it was removed it began to kick, and being pricked it flinched. It was not able to stand for two minutes, but after this it quickly recovered. Six fluid drachms of amylene weigh 240 grains, and produce 315 cubic inches of vapour; consequently there was nearly 20 per cent. of vapour in the air in this experiment.

Experiment 46. A guinea pig, a fortnight old, was placed in the jar holding 428 cubic inches, and eighty-two grains of amylene were introduced on blotting paper. It was six minutes in evaporating. The guinea pig became gradually affected, and, a minute or two before the amylene had all evaporated, it was lying unable to walk. It was allowed to remain till ten minutes had elapsed, that is, four minutes after the amylene was all converted into vapour; but it did not, apparently, become quite insensible. The limbs were never quite relaxed, and when turned over in the jar there was a little motion of the limbs and head. There was also a little quivering motion of the limbs occasionally when not disturbed, and at one time it opened and shut its mouth. On its removal, pricking the soft parts of its toes caused sometimes a slight groan. It recovered slowly and gradually. In ten minutes it was quite conscious, but not as brisk as before the experiment. There was 25 per cent. of vapour in the air the guinea pig breathed in this experiment.

Guinea pigs have a great tendency to flinch when pricked whilst they are under the influence of amylene. I did not find this to be the case with other animals.

Experiment 47. A lean, starved cat was placed in a glass jar holding 1,600 cubic inches, and 120 grains of amylene were introduced upon blotting paper. The cat became inebriated whilst the amylene was evaporating; and by the time it had all evaporated—which was four and a half minutes—the cat had sunk down in a state of insensibility. The eyes were turned downwards, so as to expose the white; but its limbs were not relaxed. In a minute or two afterwards it made no effort when rolled about in the jar. It was taken out at the end of nine minutes from the commencement of introducing the amylene. It was breathing noisily; its limbs were not relaxed; it was totally insensible to pricking of the ears and paws. It began to recover in about a minute: in two or three minutes it flinched on being pricked; it staggered for two or three minutes longer, and in ten minutes it was pretty well recovered. The amylene would produce 158 cubic inches of vapour, or very nearly ten per cent. in this experiment.

Experiment 48. A linnet was placed in a jar holding 428 cubic inches, and forty grains of amylene were introduced on blotting paper. In two minutes it had evaporated. Until it had nearly evaporated, the bird was hardly affected, only evincing a desire to escape. As soon as the amylene had evaporated, the linnet lay unable to move, but evincing consciousness and sensibility by the motion of its eyelids and eyes, and by moving its legs when it was turned over by inclining the jar. It remained in this state for three minutes, when eight grains more of amylene were introduced into the jar. The bird almost immediately closed its eyes; and it opened its bill a little, from which a little liquid flowed. The motion of its legs also ceased, and its breathing was slower. It was taken out half a minute after the last portion of amylene was introduced. It seemed quite insensible when removed, but began to recover in a few seconds. When its foot was pricked, twenty or thirty seconds after its removal, it flinched. In two or three minutes it was quite recovered. There were 12·3 per cent. of vapour in the air in the first part of this experiment; and 14·7 per cent. in the latter part.

Experiment 49. Another linnet was placed in the same jar, and forty-eight grains of amylene were introduced in the same manner. It took nearly three minutes to evaporate, hoar frost being produced on the blotting paper. The bird began to stagger when the amylene was about half evaporated; and by the time it was all evaporated, the bird was lying apparently insensible, with its eyes closed, and breathing quickly. It was allowed to remain two and a half minutes, during which it did not alter. It was often rolled about by moving the jar; and during the last minute and a half it made no effort, except once or twice a slight motion of the wings. It was taken out two and a half minutes after the amylene had all evaporated. It was quite passive, and insensible to pricking of the toes, for half a minute or so after its removal, when it began to recover, went through a stage of staggering, and was well in three or four minutes. The amount of vapour in the air, in this experiment, amounted to 14·7 per cent.

Experiment 50. Fifty grains of amylene were diffused in a glass jar holding 330 cubic inches, and a linnet was introduced by momentarily moving the lid a little to one side. It was quickly affected, and in about a quarter of a minute was lying quite insensible. It remained so, breathing quickly and naturally, and made no effort whatever when rolled about in the jar. It was allowed to remain three minutes, and there was a slight fluttering motion of the wings just before its removal. It was quite passive when removed, and insensible to pricking of the soft part of the foot. It began to recover its sensibility in three-quarters of a minute. In two minutes it was able to stand, and in six minutes it got on the perch. There was twenty per cent. of vapour in the air in this experiment.

As amylene boils nearly at the temperature of the blood, that fluid would be able to absorb about one-fifth as much as it would be able to dissolve, when an atmosphere is breathed containing twenty per cent. of the vapour, which produces a complete state of insensibility, or the fourth degree of narcotism. When ten per cent. is breathed, which has been shown to cause the second degree of narcotism, about one-tenth as much vapour as the blood would dissolve must be absorbed. In treating of chloroform and ether, it was previously shewn that the fourth degree of narcotism was caused by one twenty-eighth part as much of these agents as the blood would absorb; and the second degree by one fifty-sixth part. And these were the proportions absorbed of several other agents which are made from ordinary alcohol, and will afterwards be mentioned.

Although the proportion of amylene absorbed is large in relation to the whole quantity which the blood would dissolve, it is a very small amount on account of the extremely slight solubility of the agent. If we estimate the average amount of serum of the blood in the human adult at 410 fluid ounces, as before, then, as amylene requires 9,319 parts of watery fluids for its solution (as nearly as I could ascertain), the quantity of this agent in the system must be rather less than three grains in the fourth degree of narcotism; rather less than a grain and a half in the second degree; and a very little over two grains in the third degree of narcotism, the condition in which surgical operations are usually performed. Amylene is therefore, when absorbed, about as powerful in its medicinal properties as the alkaloids.

The following fact also proves that but a very small quantity of amylene is absorbed. In breathing this agent backwards and forwards from a small bladder containing 200 cubic inches of air, fourteen minims was the largest quantity I could put into the bladder without being rendered unconscious; but in employing a large bladder holding 670 cubic inches, I could put in forty-five minims, and breathe it backwards and forwards for some time without being rendered unconscious. With fifty minims of amylene I immediately forgot where I was; but awoke in a minute or two, seated in the same position, and with the bladder in my hand. Fifty minims of amylene would produce between six and seven per cent. of vapour in the bladder; and after the air in the lungs became mixed with that in the bladder, there would be rather more than five per cent. of vapour in it.

Viewed in the light of the small quantity which requires to be absorbed into the system to cause insensibility, amylene is a very powerful agent; but when considered in relation to the quantity which is consumed during inhalation in the ordinary way, it is very far from being powerful. This arises from the great tension and the small solubility of the vapour, in consequence of which it is, with the exception of a small fraction, expelled from the lungs again without being absorbed. In this respect it resembles, to a great extent, the nitrogen gas of the atmosphere, with which the lungs are always four-fifths filled, while the blood contains but a few cubic inches. It takes from three to four fluid drachms of amylene to cause insensibility in the adult.

I found, by my experiments on animals, that amylene is, like chloroform and some other agents, capable of causing sudden death by over-narcotism of the heart, and paralysis of that organ; but that it is more difficult to cause this kind of sudden death with amylene than with chloroform.

Experiment 51. One hundred and twenty grains of amylene were made to evaporate in a jar holding 330 cubic inches, and a full grown guinea pig was suddenly introduced, the cover being partly removed for a moment. It was allowed to remain for about a minute, when the breathing became of a gasping character. Being taken out, and the stethoscope applied immediately to the chest, the heart could not be heard to beat; and its action did not return, although the gasping continued for about a minute. There was nearly 48 per cent. of vapour in the air in this experiment, except that a small quantity might escape as the guinea pig was introduced. I had tried guinea pigs with smaller proportions of vapour in the air, but had not succeeded in arresting the action of the heart.

The lungs were rather congested, and the right cavities of the heart were filled, and somewhat distended with coagulated blood.

Experiment 52. A kitten, six weeks old, was placed in a jar holding 330 cubic inches, after ninety-five grains of amylene had been made to evaporate and diffuse itself. The kitten remained three-quarters of a minute in the jar, and was suddenly taken out. It was scarcely insensible on its removal, but soon became so. The stethoscope was applied, and the heart was found to be beating rapidly. The kitten quickly recovered.

One hundred and six grains of amylene were made to evaporate in the same jar, and the kitten was quickly introduced, as before, by moving the cover for a moment. It was allowed to remain for half a minute, and removed with the same symptoms and result as before.

The same quantity of amylene was employed, and the kitten was introduced again, and allowed to remain for fifty seconds. On its first removal the heart was not beating, but the kitten was gasping; and just afterwards the heart was heard to be beating rapidly. The kitten quickly recovered.

One hundred and twenty grains of amylene were allowed to evaporate in the jar, and the kitten was introduced again. It was allowed to remain a minute, and was taken out as the breathing appeared to be on the point of ceasing. The heart was beating when the stethoscope was employed, and the kitten quickly recovered. It seemed impossible to kill it with amylene, except by allowing it to remain and inhale the vapour, by those gasping inspirations which took place when the action of the heart was arrested, and which restored the action of this organ, when the kitten was withdrawn from the vapour. In the different parts of this experiment there were 37, 42, and 47 per cent. of amylene in the air.