A number of observations have been recorded tending to show that methyl alcohol is distinctly more poisonous than its ethyl homologue. This toxic character has been ascribed to the oxidation of the methyl alcohol in the tissues to formaldehyde, which, as is well known, has a strong chemical action on nitrogenous organic substances. Or again, it has been attributed also to the further oxidation-product formic acid, which appears in the urine in cases of methyl alcohol poisoning, and has been found in the cadaver after death: this acid is said to cause fatty degeneration of the blood-vessels in the sheaths of the optic nerve and choroid membrane, leading to serious affection of the eyesight.1

As regards instances of actual poisoning through drinking methyl alcohol in quantity, the best known is perhaps the Berlin case which occurred in 1911. A factitious "brandy" or "schnapps" had been concocted with methyl and ethyl alcohols in the proportion of about 4 parts of the former to 1 part of the latter, and drunk by a large number of people, with the result that there were 95 cases of illness and 70 deaths.1 Another instance is recorded, with the symptoms, by Dr. C. A. Wood as occurring in Indiana during 1911.

1 Kasass, Zentr. Biochem. Biophys., 15, 205.

Five men made a mixture of one gallon of wood alcohol and three gallons of grain (ethyl) alcohol, and all drank freely of it, with fatal results. Blindness came on about six to eight hours before death.2

According to observations made by Nicloux and Placet,3 large intravenous doses of methyl alcohol are relatively less toxic than ethyl alcohol; but in repeated small doses every twenty-four hours the reverse is the case. This appears to be due to the cumulative effect obtained, since methyl alcohol is eliminated more slowly, and is less readily destroyed in the tissues, than is ethyl alcohol.

The latter phenomenon is illustrated by some experiments on dogs carried out by Voltz and Dietrich.4 It was found that after administration of methyl alcohol (2 c c. per kilo. of body weight), only 39 per cent, was oxidised in the tissues during forty-eight hours. On the other hand, when ethyl alcohol was given under similar conditions, about 90 per cent. of the alcohol was oxidised and destroyed in the tissues during a much shorter time, namely, fifteen hours.

Numerous references to papers on the toxicology of methyl alcohol are given by E. Merck.5 The conclusions summarised ' show that methyl alcohol itself, when habitually used, or when taken in a single large dose, may act as a poison, and that " the toxicity is not due to the presence of impurities in the preparation." Some persons are able to take large doses of methyl alcohol without apparent harm. It is, however, impossible to say beforehand how large a dose will show an injurious effect. According to one investigator (Ruhle), the lethal dose varies between 50 and 100 grams. "but the toxic dose is much less, and blindness may ensue after doses of only 7 or 8 grams."

Olivari6 found that with pure methyl alcohol the minimal lethal dose for small animals (guinea-pigs, mice, frogs) was about 10 grams per kilogram of body weight, the dose ranging from 95 to 115 in the three animals mentioned.

1 Zeitsch. Nahr. und Oenussm., 1912, 24, 7.

2 Blindness from Wood Alcohol, pub. American Mod. Assoc.

3 J. Physiol. Path., 14, 916. 4 Biochem. Zeitsch, 1912,. 40, 15. 5 "Annual Report," 1912. 6 Chem. Zentr., 1913, 1, 1780.