The neutral esters are as a rule insoluble in water and distil unchanged; on the other hand, the acid esters are generally soluble in water, are non-volatile, and form salts with bases.
The azines are mostly yellow in colour, distil unchanged and are stable to oxidants.
The nitro compounds are colourless, somewhat pleasant smelling liquids, which distil without decomposition and possess boiling points much higher than those of the isomeric nitrous esters.
On distilling such a mixture, a mixture of constant composition will distil first, leaving in the distilling flask one or other of the components according to the composition of the mixture.
As the distillation proceeded one layer would diminish more rapidly than the other until only the latter would remain; this would then distil as a completely miscible mixture.
This will then distil at a constant temperature.
A violet odour and a fragrant oil were said to distil from her tomb; and when it was opened nine months afterwards the flesh was found uncorrupted.
The mono-nitro compounds are stable and distil without decomposition; they have a pale yellow colour and possess an agreeable odour.
Since many substances decompose either at, or below, their boiling-points under ordinary atmospheric pressure, it is necessary to lower the boiling-point by reducing the pressure if it be desired to distil them.
To obtain the free acid it is best to dissolve the diazohippuramide in dilute soda, warm the solution to ensure the formation of the sodium salt, and distil the resulting liquid with dilute sulphuric acid.