CHAP. X.
On the SWEETENING PROPERTIES of FIXED AIR.
THE very curious fact, that fixed air not only preserves bodies from becoming septic, but is also possessed of the power of restoring sweetness to them when actually putrid, seemed to be established by a number of very accurate experiments adduced in support of the doctrine by its ingenious author. This has, however, lately been controverted by a learned writer, who has favoured the public with an Experimental Inquiry concerning the causes which have been generally said to produce putrid diseases, in which he has recounted several experiments, in direct contradiction to those of Dr. Macbride. The authorities of both these gentlemen deserve considerable attention, and it might seem presumption in me to attempt to decide between them, had I only my own opinion to adduce; but as the accuracy of the following trials was witnessed by a Physician, well known for his medical and philosophical writings, I feel the less diffidence in submitting them to the public. They were made with a view, only, to my own information, having in one of the former chapters recommended Magnesia to be taken in the act of effervescence with an acid, as a corrector and evacuant of putrid bile; but as the event appeared to be so satisfactory, and as a determination of this point is the more important, from the late introduction of fixed air as an article of the materia medica, I hope I shall not be deemed to have impertinently obtruded into the dispute by relating them, and endeavouring to point out what, probably, has been the cause of Dr. Alexander's drawing conclusions, so contrary to those of the other celebrated experimentalist.
In the experiments which Dr. Alexander has related in support of his opinion, he has made use of the following methods. He included pieces of putrid mutton in bladders, one containing four ounces in measure of fixed air from fermenting wort; another the same quantity from wort with a piece of putrid mutton in it; and the third, only about half the quantity from a mixture of bread, water, and saliva. In another experiment, he exposed a slice of beef that had just begun to have the putrid smell, to a stream of air brought over from an effervescing mixture of distilled vinegar and salt of wormwood. In a third, the putrid flesh was suspended in the neck of a wide mouthed bottle, while four ounces of distilled vinegar were made into spirit. minderer. In a fourth, four ounces of air from bottled small beer were confined twenty-four hours with the putrid substance, which in a fifth experiment was put into the neck of a bottle of small beer, while it fermented before the fire for half an hour. In a sixth, the septic body was included in a bottle with eight ounces of air from an effervescing mixture of common vinegar and salt of hartshorn. In one only, out of all these experiments, he found the beef in any-wise sweetened, and even in that single instance, though he at first thought the piece a little changed, yet when washed it recovered its putrid smell. However he confesses, that by bringing over fixed air from several other fermenting and effervescing mixtures, on pieces of meat just beginning to putrefy, they were rendered a little sweeter, though never to such a degree, as entirely to lose their putrid taint.
So very different an account of so interesting a subject was truly mortifying: The old adage, experientia fallax, judicium difficile, seemed to be too applicable to the present occasion. Some cases, in which fixed air used medicinally as an antiseptic, appeared to have produced good effects, had occurred to some of my medical friends[v], and I even flattered myself that I had directed it to good purpose in an instance or two. But if the theory on which this practice was founded should be false, the whole superstructure seemed likely to be destroyed. On revising Dr. Alexander's book, I imagined that I had discovered some thing in the conducting of his experiments, which might account for their terminating so differently from those of Dr. Macbride.
The largest quantity of fixed air which Dr. Alexander made use of in any of these experiments was eight ounces in measure, and in one instance, only two ounces were employed to sweeten the putrid substance. In that where the meat was suspended in a wide mouthed bottle while the vinegar was made into spirit. minderer. no method seems to have been taken to retard the too rapid flight of the fixed air, which, from the quick distribution of the salt, would be soon dissipated. From hence I suspected, that a larger atmosphere, or a longer continued stream of fixed air might be requisite to restore septic bodies to perfect sweetness; and in order to decide this point, the following experiments were instituted, having previously obtained some slices of beef so exceedingly putrefied as to render the fœtor of them scarcely tolerable.
EXPERIMENT XXIX.
A bottle capable of containing three pints was filled with water, and inverted into a bason of the same; a tube which communicated with another bottle, in which was an effervescing mixture of chalk and oil of vitriol, was then introduced into the mouth of the former, and a stream of fixed air continued, till the whole of the water was driven out by it. A piece of the above-mentioned putrid beef, fastened by a string to a cork, was conveyed into the bottle, which was corked before it was taken out of the water. The beef, after having been suspended in this atmosphere of fixed air for thirteen hours, was very considerably, though not entirely sweetened. But the air in the bottle seemed to have acquired all the putrid smell of which the flesh had been deprived. Another slice of the same beef was not at all sweetened by exposure, during the same time, to the open air.
EXPERIMENT XXX.