No method is at present known of separating amylene from the products which come over with it, except a number of distillations; and although these may be carried so far as to obtain a small quantity almost pure, the price of it would be too great to admit of its employment for inhalation. For this purpose, one must be content with a product approaching to purity. Dr. Debout, in an article on amylene,[[174]] says that the boiling point commences at 28° (82° Fah.), and rises gradually to 40° or 45° (104° or 113°) in the best products which have been obtained by Mr. Bullock of London, M. Hepp of Strasbourg, and the house of Ménier at Paris.
M. Duroy published an elaborate paper on amylene, on April 9th, 1857.[[175]] In this paper, he gives the result of an examination of four specimens of amylene: the first, which he calls A, was amylene made by Mr. Bullock; the second (B) was the amylene of M. Ménier; the third (C) was some that he had prepared according to the process of M. Hepp; the fourth (D) was amylene which he had obtained by a process which he described. In this process, he employed dry chloride of zinc and amylic alcohol. M. Balard recommended a solution of chloride of zinc of a certain strength to be used. I may state, however, that Mr. Bullock had from the first used dry chloride of zinc.
The following table shows the temperature at which the different specimens began to boil, and the temperature to which they rose before being boiled entirely away.
| A 30° | cent. | = 86° | Fah. | to 46° | cent. | = 115° | Fah. |
| B 29 | „ | = 84 | „ | to 75 | „ | = 167 | „ |
| C 30 | „ | = 86 | „ | to 62 | „ | = 143 | „ |
| D 31 | „ | = 88 | „ | to 57 | „ | = 134 | „ |
Mr. Bullock’s amylene went through the smallest range of temperature whilst boiling away.
M. Duroy found that potassium was oxidized to a certain extent in all these specimens of amylene, and a small quantity of hydrogen gas was produced, showing that they did not consist entirely of hydrocarbons, but that there distilled over with them a small quantity, either of amylic alcohol, or amylic ether.
The following table shows the cubic centimetres of hydrogen gas which were disengaged from three grammes of each of the different kinds of amylene.
| A | 64 |
| B | 91 |
| C | 75 |
| D | 69 |
Examined in this way, Mr. Bullock’s amylene showed the smallest quantity of impurity; and, next to that, the amylene made by M. Duroy.
M. Duroy found that amylene can be purified from the substances containing oxygen by distilling it again with dry chloride of zinc. He was able to obtain pure amylene, boiling steadily at 35° cent., but to get at this result he made so many distillations that he had only forty grammes of amylene from five litres of amylic alcohol.