When a solution of the strength of about i in zo is applied to the skin it produces a local anaesthesia which lasts for many hours.
Bartlett, of Dr Horace Wells (1815-1848), the discoverer of anaesthesia; and one, by E.
Morphine-scopolamine anaesthesia was introduced in 1902 by Steinbiickel.
It is largely used in dentistry and slight surgical operations to produce local anaesthesia, and is known by the trade-name kelene.
Some of them are so volatile that they produce their effects when inhaled, others when sprayed upon the skin cause intense cold and then anaesthesia; but taken in the broadest sense the action of all of them after absorption into the blood is very similar, and is exerted upon the central nervous system, more especially the cerebrum.
In such cases the acute collapse occurs in company with both superficial and deep anaesthesia of the limbs, and is soon followed by coma terminating in death.
The subsequent experiments of Snellen, Senftleben, and, more lately, of Turner, seem to show that if the eyeball be protected from the impingement of foreign particles, an accident to which it is liable owing to its state of anaesthesia, the ulceration may be warded off indefinitely.
It has been used by some surgeons for the production of anaesthesia previous to the administration of ether or chloroform, but the use of the method is now more usually relegated to obstetric practice.
Applied to the conjunctiva it causes anaesthesia, dilatation of the pupil, diminution of the intraocular tension, and some interference with accommodation.
Thus there may be hyperaesthesia, anaesthesia, paralysis, or alterations of nutrition, such as wasting of muscles, whitening of the hair, &c.
Proposals have been made to employ hypnotism as a method of producing anaesthesia for surgical purposes, but there are two grave objections to such employment.
The fourth ocular result of administering atropine is the production of a slight but definite degree of local anaesthesia of the eyeball.
