Practical organic chemistry / by Julius B. Cohen.

  • Julius B. Cohen
Date:
1908
Catalogue details

Licence: Public Domain Mark

Credit: Practical organic chemistry / by Julius B. Cohen. Source: Wellcome Collection.

    49/380 page 29
    one atom of hydrogen. Consequently the observed density must be multiplied by two in order to obtain the molecular weight compared with one atom of hydrogen. Vapour Density Method (Victor Meyer).—This method, which is generally employed for substances which volatilise without decom¬ position, is known as the air displacement method of Victor Meyer. It con¬ sists in rapidly vaporising a known weight of a sub¬ stance at a constant tem¬ perature at least 40—50° above its boiling-point in a special form of appar¬ atus, which admits of the displaced air being col¬ lected and measured. The volume occupied by a given weight of the sub¬ stance under known con¬ ditions is thus ascertained and from these data the density is calculated. The following apparatus is re¬ quired :— 1. A Victor Meyer Ap¬ paratus as shown in Fig. 27. It consists of an elongated glass bulb with a narrow stem, and a capillary side-tube. It is provided with a well¬ fitting rubber cork, which can be pressed easily and tightly into the open end of the stem. The apparatus is clamped within an outer jacket of tin plate or copper, which holds the boiling liquid required to produce a constant temperature. It is represented as transparent in the Fig.
    digitised image 1
    digitised image 2
    digitised image 3