108 Proceedings of the British Association. 



ance of fermentation, either then, or in double the time. As the extract 

 of nux vomica is known to be a poison to infusoria (animalcules), but 

 not to vegetating mould, while arsenic is a poison to both, by these tests 

 it was proved that the living particles ins'trumental to fermentation be- 

 longed to the order of plants of the Confervoid family. Beer yeast, ac- 

 cording to Schwann, consists entirely of microscopic fungi, in the shape 

 of small oval grains of a yellowish white colour, arranged in rows oblique 

 to each other. Fresh grape must contains none of them ; but, after be- 

 iug exposed to the air at 20° R., for 36 hours, similar grains become 

 visible in the microscope, and may be observed to grow larger in the 

 course of an hour, or even in half that time. A few hours after these 

 plants are first perceived, gas begins to be disengaged. They multiply 

 greatly in the course of fermentation, and at its conclusion subside to 

 the bottom of the beer in the shape of a yellow white powder. 



Mr. Martineau objected to the low temperatures for making extracts 

 mentioned by Dr. Ure. — Mr. Black, on being referred to by Dr. Ure, 

 stated that the temperatures used by distillers and brewers were very 

 different, in consequence of the difference of the materials used in brew- 

 ing distillers' wash and brewers' wort. The distillers use sometimes 

 only one-tenth part of malt, and the remainder bruised barley, or other 

 corn; and were they to use such high temperatures, in the first mashing, 

 as those used by brewers who use only malt, the mass would get coagu- 

 lated like thin batter, — or the tun set, as it is technically termed. The 

 distillers, however, after making their first infusion at much lower tem- 

 peratures than brewers, bring them up, before running off the worts, by 

 the addition of water, at as high a temperature as any used by the 

 brewer. Mr. Black seemed also to object to so high a temperature as 

 Mr. Martineau mentioned for the first infusion, 180° F., but preferred 10° 

 or 12° lower, the heat being afterwards brought up in the same way as 

 in the distillery. 



Section C. — Geology and Geography. — Thursday. 



Mr. Bowman read a paper on some skeletons of fossil vegetables, 

 found by Mr. Binney, in the shape of a white impalpable powder, under 

 a peat bog near Gainsborough, occupying a stratum four to six inches in 

 thickness, and covering an area of several acres. It remained unchanged 

 by the sulphuric, hydrochloric, and nitric acids, and by heat, and was 

 concluded to be pure silica, in a state of extremely minute subdivision. 

 On submitting it to the highest power of the compound microscope, it 

 was found to consist of a mass of transparent squares and parallelograms 

 of different relative proportions, whose edges were perfectly sharp and 

 smooth, and the areas often traced with very delicate parallel lines. On 

 comparing these with the forms of some existing Conferva?, Mr. Bow- 

 man found the resemblance so strong, that he entertained no doubt they 

 were the fragments of parasitical plants of that order, either identi- 



