Nitrogen, Phosphorus, Vanadium, Arsenic, Niobium, Antimony, Tantalum, Bismuth.

In the heading to this class I have substituted the word elements for metals, for nitrogen and phosphorus belong to it, although they are non-metallic elements.

They form analogous compounds with oxygen and hydrogen.

l

2

3

4

5

Nitrogen........

N ...

N2O ...

N2O2 ...

N2O3 ...

N2O4 ...

N2O5 ...

NH3

Phosphorus ...

P

...

P2O3

p2O5 ...

PH3

Vanadium........

V ...

V2O ...

V2O2...

V2O3

V2O4 ...

V2O5 ...

Arsenic ........

As

...

As2O3

...

As2O5

AsH3

Antimony ......

Sb

...

Sb2O3

...

Sb2O5 ...

SbH3

Bismuth .......

Bi

...

Bi2O3

...

Bi2O5

Nitrogen. N; 14. Non-officinal.

Nitrogen when free is chemically inactive, and does not readily unite with other elements. It is also physiologically inactive, but has been used as an anaesthetic. The anaesthesia is due to asphyxia, from absence of oxygen; but as the carbonic acid is constantly removed by the inhalation of nitrogen, the symptoms of irritation produced by it in ordinary asphyxia are absent.

Combined with hydrogen, as in ammonia and salts of ammonium, nitrogen stimulates and then paralyses nerve-centres, motor nerves and muscles (p. 144); and the action varies in the salts, for while the chloride affects the spinal cord, the iodide paralyses motor nerves and muscles. When nitrogen is combined with carbon, the activity of the substance depends on whether the nitrogen is pentad or triad, as in in the first of which, with one free affinity belonging to the nitrogen, the compounds are very poisonous, while in the second, where the free affinity belongs to the carbon, the compounds are comparatively harmless.

The 1st, 3rd, and 5th

The 1st, 3rd, and 5th of its oxygen compounds in the above table can take up the elements of water and of metallic oxides to form salts.

Hydrogen Salt.

Hyponitrous acid

H2ON2O or HNO.

Nitrous acid

H2ON2O3 or HNO2.

Nitric acid

H2ON2O5 or HNO3.

Metallic Salt, e.g. of Potassium.

Potassium hyponitrite

K2ON2O or KNO.

„ nitrite

K2ON2O3 or KNO2

„ nitrate

K2ON2O5 or KNO3

The acid compounds of nitrogen with oxygen resemble those of phosphorus and arsenic in this, that the nitrites are considerably more active than the nitrates, just as the phosphites and arsenites are more active than the phosphates and arseniates. The action of nitrites on the organism was first investigated in the case of nitrite of amyl, but by some unpublished experiments made in Professor Ludwig's laboratory in 1869-70, I satisfied myself of the correctness of Dr. B. W. Richardson's observation,1 that other nitrites, such as those of ethyl and sodium, had an action on the blood-pressure similar in kind though less in degree. In other experiments Dr. Gresswell and I found that the nitrites of propyl and butyl had also this action, and that all nitrites were muscular poisons.2 Mr. Tait and I found that nitroglycerine had an action resembling the nitrites both in its effect on blood-pressure and the change it caused in the colour of the blood, but the headache it produced deterred us from employing it in the treatment of patients.3

Nitrous Oxide. Nitrogen Monoxide. Laughing gas. N2O. Not officinal.

Preparation. - By heating nitrate of ammonium.

Action. - When a mixture of nitrous oxide and air is inhaled it causes excitement, generally characterised by fits of involuntary laughter, dancing, singing, and shouting, although it sometimes appears to arouse pugnacity. When inhaled pure, it produces, first of all, a feeling of increased circulation through the body generally, accompanied by warmth and a little singing in the ears. If the inhalation be now stopped, the effect may pass off, but occasionally, after a few breaths of pure air have been taken, the same excitement may ensue which is usually produced by the inhalation of mixed air and gas. On one occasion, having inhaled pure gas for a short time, I felt a little warmth of the skin and a humming in the head, and, thinking it was time to desist, laid down the mask of the inhaler. After a few breaths of fresh air, I noticed that on attempting to speak, the speech was slow and hesitating. An electric shock then seemed to shoot through the spine, and I was seized with an uncontrollable desire to laugh, jump, and throw the arms about, while the perceptive faculties appeared quite unaffected. Although unable to control my movements, I was perfectly conscious of their ludicrous nature, and was astonished that two men who were sitting by, and who afterwards informed me that they thought the whole thing a bad joke, were able to preserve their gravity. After lasting for one or two minutes, the effect of the gas suddenly and completely passed off.

1 B. W. Richardson, Brit. and For. Med. Chir. Rev., July, 1867.

2 St. Bartholomew's Hospital Reports, 1876, p. 143. 3 Ibid. p. 140.

When inhalation is continued for a longer time, the feelings of warmth and buzzing in the ears are succeeded by gradually increasing dimness of perception; sight, sounds, and tactile impressions become much dimmer than usual: and then the person becomes unconscious. At this time the face usually assumes a livid aspect, and during the period of insensibility small operations may be performed without the patient being the least aware of them. When the administration of the gas is stopped, recovery quickly and completely occurs, often passing off without leaving any after-effects, though occasionally more or less headache is experienced for some hours. No stage of exhilaration such as that which has already been described as occurring after the administration of a small quantity of nitrous oxide is noticed during recovery from complete narcosis.

Nitrous oxide appears to act as an anaesthetic chiefly by depriving the nerve-centres of oxygen. As the inhalation of pure nitrogen has a similar anaesthetic power, the exhilarating effect of small doses of nitrous oxide seems to show besides that it has a special relation to the nerve-centres.

Uses. - It is useful as an anaesthetic for extraction of teeth, evulsion of the toe-nail, and other minor operations. The intense venosity of the blood which occurs during its use renders it unsuitable for continued administration, and therefore inadmissible in the case of lengthy operations. It is sometimes used to commence anaesthesia, ether being given after the patient is unconscious.

Mode of Administration. - The most convenient mode of administering it is to have it condensed in a large iron bottle, from which the gas may be readily conveyed to the patient by means of a flexible tube attached to a mask. The mask ought to be provided with a margin of inflated india-rubber, so that it will fit perfectly tight to the face, and thus prevent the escape of gas. After the operation it is well to make the patient perform some act, such as taking hold of the glass of water after a tooth has been extracted, in order to hasten the return of consciousness.