588 PROFESSOR ANDERSON ON THE PRODUCTS OF THE 



length the bottom of the flask may be heated nearly red hot, while a very insig- 

 nificant quantity of oil distils up. In performing this process, glass flasks were 

 corroded by the caustic potash long before the action was complete, and it was 

 found very convenient to employ copper flasks made by the electrotype process. 

 A plaster of Paris mould was taken from a glass flask of convenient size and 

 shape ; and from that a wax cast was made and electrotyped in the usual way. 

 After about a week the copper was sufficiently thick for use. In such flasks 

 pyrrol was boiled for a day or two with caustic potash, the heat being raised as 

 high as an Argand or Bunsen's gas-lamp would bring it. A bent tube was then 

 fitted into the mouth of the flask, and the heat again applied, so as to distil off all 

 the oil that could be obtained. The distillate had the smell of pyrrol mixed more or 

 less distinctly with that of picoline, and the preponderance of the latter smell 

 depended on the quantity of potash having been sufficiently large to retain the 

 true pyrrol, which, however, it was not possible to do entirely, even when a very 

 large excess of potash was used. When the whole of this oil had distilled, the 

 bent tube was removed from the mouth of the flask, and the still fluid potash 

 poured out on a copper plate. 



On cooling, it solidified into a hard white mass with a yellowish tinge, which, 

 when perfectly dry had no smell, but it was only necessary to breathe upon 

 it to cause it to exhale a delightful etherial and fragrant odour, not unlike 

 that of chloroform, but softer and less pungent. When thrown into water 

 the potash gradually dissolved, and a transparent and colourless oil col- 

 lected on the surface of the solution, from which it was separated either 

 by a pipette or by distillation. The potash solution on saturation with sul- 

 phuric acid evolved the smell of a fatty acid, and when distilled, yielded a 

 fluid which reddened litmus strongly, and had a smell resembling that of 

 valerianic acid. The distillate was saturated with carbonate of soda, and 

 the solution evaporated to complete dryness and extracted with absolute alco- 

 hol. The alcoholic fluid was again evaporated, the residue dissolved in 

 water, and a quantity of solution of nitrate of silver insufficient for com- 

 plete precipitation added to it, and the precipitate was collected on a filter 

 and washed. Another quantity of nitrate of silver was then added, and the 

 precipitate collected, and finally, enough of the nitrate was used to throw the 

 remainder of the fatty acids in the fluid. In this way three different silver 

 salts were obtained, which were separately analysed. The first precipitate 

 gave : — 



{6-273 grains of silver salt gave 

 6-510 ... carbonic acid and 

 2-452 ... water. 



f 5-192 grains of silver salt gave 

 2-697 ... silver. 



