tracheal insufflation is the method by means of which a mixture of air and ether is driven into the trachea (windpipe) by external pressure through a tube inserted into the trachea through the larynx. Anesthesia by colonic absorption of ether is the method of introducing ether into the intestines through the rectum. A similar method employs a mixture of oil and ether. There is also spinal anesthesia, injecting cocain or another agent into the spine; and intravenous anesthesia, introducing the agent directly into the blood by injections into the veins. All of these methods, however, are not as common as the inhalation method and are generally used only in special cases.

A method in quite common use is local anesthesia; rendering insensible to pain only a restricted portion of the body. Compression of nerves and blood vessels. has already been mentioned. In the sixteenth century Serverino, an Italian surgeon, called attention to the local application of cold as a means of reducing sensibility. In 1807, Napoleon's surgeon noticed on the retreat from Moscow that, in amputations performed on the battlefield at very low temperatures, the sensibility of the limbs was completely abolished. Freezing mixtures were occasionally used, being directly applied to the body. The modern use of cold was introduced with the invention of the ether spray in 1866 by Sir Benjamin Ward Richardson. Ethyl chloride is now used as the freezing agent, it is sprayed on the part to be anesthetized until the part is white and frozen. Local anesthesia by the application of special drugs was made possible by the invention of the hypodermic syringe and by the demonstration in 1884, of the anesthetic action of cocain. The drug is injected into the neighborhood of the nerve trunks with the hypodermic syringe. Adrenalin is used. in addition to cocain and novocain is also used in place of it. The success of local anesthesia by injections is due to a process of nerve blocking which is used a great deal in dental practice.

In the seventy-eight years since Morton's discovery 223 patents have been issued on apparatus for producing

anesthesia; 16 in the first 26 years; 70 in the next, and 137 in the last 26 years. This is a fair indication of the general progress.

Morton's first patent describes the inhaler he used, which as seen from the patent was very simple in construction and operation. It consisted of a flask containing a sponge saturated with ether. Holes in the flask allowed air to pass through. The extremity of the neck was placed in the patient's mouth and his nostrils held closed. The British patent has a drawing and shows a mask to cover the mouth and nose and having inhalation and exhalation valves.

Probably the first and simplest method of administering ether is to place a piece of cloth saturated with ether adjacent the nostrils. Ether alone is now generally administered by the open or drop method. A mask consist ing of a wire frame and means for holding a piece of gauze over the frame is used. The ether is dropped either from the original container or from a special dropper onto the gauze from which it evaporates and is inhaled.

The closed method of administering ether was developed in England in 1872. The inhaler used generally consists of a face-piece, a cylinder containing valves mounted on the face-piece and a bag to be filled with gas, attached to the cylinder. Two or more bags are also used for combinations and sequences of different gases.

Chloroform is also administered by the drop method and by inhalers similar, in general, to those used for ether.

The greatest development in anesthetic apparatus has been, however, in machines used for administering a mixture of nitrous oxide and oxygen, due to the great use of this mixture in dental surgery. The machines now in use consist, usually, of a stand holding oxygen and nitrous oxide containers, pressure reducing valves, a mixing chamber in which the two gases are mixed, means for varying the relative proportions of the gases and for varying the amount of the mixture delivered, a tube for delivering the mixture to an inhaling mask, and

pressure gauges and proportion scales. The differences in the various patented machines lie in the means for varying and controlling the relative proportions of the gases. Other features used on most machines are, an ether container and dropper, so that ether may be used if desired, an electrical heating element in the mixing chamber, and a re-breathing bag. When the latter is used the patient exhales into the rebreathing bag, the exhaled gas mixes with the new gas and is breathed over again.

Inhalers for anesthetics do not differ in structure from inhalers used for general medical purposes and they are classified together under Inhalers in Class 128, Surgery. The particular subclasses containing patents specifically relating to anesthesia are given below.

200

201

202

203

204

205

Tubular, (2 patents)

Oral, (1 patent)

Rebreathing-bag combination,

Gas-holder combination,

Pressure varying chamber, (1 patent)
Oronasal,

"Anaesthetics Ancient and Modern; an Historical Sketch of Anaesthesia." Burroughs, Wellcome & Co.,

London, 1907. Bigelow, Henry J.; "Surgical Anaesthesia, Address and Other Papers." Boston, 1900. Garrison; "History of Medicine", 1924. Gwathmey, J. T.; "Anesthesia", New York, 1924. Nevius, L. W.; "The Discovery of Modern Anesthesia. By Whom Was It Made? A Brief Statement of Facts." New York, 1894. Simpson, Sir J. Y.; "Anesthesia, etc." New York, 1872. Smith, A. E.; "Block Anesthesia and Allied Subjects.

PATENT NOVELTY.

In order that a patent may be valid it must possess the element of novelty. (Novelty in different countries has different definitions. In this country it means novelty within the realm. Publication of the invention abroad before the date of the British application does not invalidate a British patent. On the other hand publication by way of a foreign specification reaching this country before the date of the British application does detract from the novelty of the British case.) There are certain specific exceptions to lack of novelty provided by the Patent Act. A British specification more than fifty years old of itself will not invalidate a British patent, and it is possible therefore to re-patent something described in a specification more than fifty years old if that be the only publication of the alleged invention. Very little has been done in the way of defining just what it required in addition to the specification more than fifty years old to enable it to invalidate a later patent.

In a case not long ago before the courts the judge granted a certificate of costs in respect to a specification more than fifty years old, thereby practically admitting it, his reason presumably being so far as one can ascertain from the reports, that examples of manufacture according to the specification or on somewhat similar lines had been seen in museums.

A provisional specification which has been printed,

but not followed by a complete specification is not at the present day considered to be such a publication as will detract from the novelty of a later application. A specification for the same invention by the same inventor filed abroad, accepted and sent to this country before the British application is lodged will not bar the grant of a valid British patent provided that the British application is lodged under the provisions of the International Convention for the protection of industrial property. According to this the British application must be filed within one year of the filing of the first application foreign. to this country. If not filed under the provisions of this convention the British patent in the circumstances mentioned would be invalid having no novelty in view of the prior publication.

Publication of an invention at an exhibition does not detract from novelty if certain conditions are fulfilled. These are dealt with in Section 45 of the Act of 1907. This section has been amended by the Act of 1919, so that it now covers in addition the reading of a paper by an inventor before a learned society or the publication of the paper in the society's transactions. The first part of the section as it now stands reads as follows:

"The exhibition of an invention at an industrial or international exhibition, certified as such by the Board of Trade, or the publication of any description of the invention during the period of the holding of the exhibition, or the use of the invention for the purpose of the exhibition in the place where the exhibition is held, or the use of the invention during the period of the holding of the exhibition by any person elsewhere, without the privity or consent of the inventor, or the reading of a paper by an inventor before a learned society, or the publication of the paper in the society's transactions, shall not prejudice the right of the inventor to apply for and obtain a patent in respect of the invention or the validity of any patent granted on the application, provided that"(a) The exhibitor, before exhibiting the invention, or the person reading such paper or permitting such pub