~Chloroform~ (CHCl_{3}). This can be made by treating methane with chlorine, as just indicated, although a much easier method consists in treating alcohol or acetone (which see) with bleaching powder. Chloroform is a heavy liquid having a pleasant odor and a sweetish taste. It is largely used as a solvent and as an anaesthetic in surgery. ~Iodoform~ (CHI_{3}). This is a yellow crystalline solid obtained by treating alcohol with iodine and an alkali. It has a characteristic odor and is used as an antiseptic. ALCOHOLS When such a compound as CH_{3}Cl is treated with silver hydroxide the reaction expressed by the following equation takes place: CH_{3}Cl + AgOH = CH_{3}OH + AgCl. Similarly C_{2}H_{5}Cl will give C_{2}H_{5}OH and AgCl. The compounds CH_{3}OH and C_{2}H_{5}OH so obtained belong to the class of substances known as _alcohols_. From their formulas it will be seen that they may be regarded as derived from hydrocarbons by substituting the hydroxyl group (OH) for hydrogen. Thus the alcohol CH_{3}OH may be regarded as derived from methane (CH_{4}) by substituting the group OH for one atom of hydrogen. A great many alcohols are known, and, like the hydrocarbons, they may be grouped into series. The relation between the first three members of the methane series and the corresponding alcohols is shown in the following table: CH_{4} (methane) CH_{3}OH (methyl alcohol). C_{2}H_{6} (ethane) C_{2}H_{5}OH (ethyl alcohol). C_{3}H_{8} (propane) C_{3}H_{7}OH (propyl alcohol). ~Methyl alcohol~ (_wood alcohol_) (CH_{3}OH). When wood is placed in an air-tight retort and heated, a number of compounds are evolved, the most important of which are the three liquids, methyl alcohol, acetic acid, and acetone. Methyl alcohol is obtained entirely from this source, and on this account is commonly called _wood alcohol_. It is a colorless liquid which has a density of 0.79 and boils at 67 deg.. It burns with an almost colorless flame and is sometimes used for heating purposes, in place of the more expensive ethyl alcohol. It is a good solvent for organic substances and is used especially as a solvent in the manufacture of varnishes. It is very poisonous. ~Ethyl alcohol~ (_common alcohol_) (C_{2}H_{5}OH). 1. _Preparation._ This compound may be prepared from glucose (C_{6}H_{12}O_{6}), a sugar easily obtained from starch. If some baker's yeast is added to a solution of glucose and the temperature is maintained at about 30 deg., bubbles of gas are soon evolved, showing that a change is taking place. The yeast contains a large number of minute organized bodies, which are really forms of plant life. The plant grows in the glucose solution, and in so doing secretes a substance known as _zymase_, which breaks down the glucose in accordance with the following equation: C_{6}H_{12}O_{6} = 2C_{2}H_{5}OH + 2CO_{2}.