339 



yield of even 2i to 3 per cent, of nitrogen from tlie dry leaves is not 

 common. 



Tannin in the manufacture of beer. — We liave already refeiTed 

 to the increasing nse of tannin as obtained from the grape, in the treat- 

 ment of wine, for the special object of arresting fermentation and 

 preventing change beyond a desired point. A similar application is 

 now made with much success in the preparation of beer ; and the result, 

 according to critical authority, has been to establish a new epoch in this 

 manufacture. It is to the presence of tannin in the leaves of the hop that 

 its preservative peculiarities are due ; and in the tannin of the nut-gall 

 we have the same agent in greater intensity, 75 grains of tannin exert- 

 ing as positive an action upon beer as a pound of the best hops. By 

 taking tannin dissolved in ten times its weight of warm water and add- 

 ing it to the wort, a complete clarification will take place, and on cool- 

 ing a deposit will be thrown down. In all cases where the peculiar- 

 aroma and bitter substance of hops are not desired, but a sweet wine or 

 beer is to be produced, the hops can always be replaced completely and 

 with advantage by the tannin. The use of this new material allows the 

 manufacture of several new kinds of beer, and obviates the necessity of 

 using any other modes of clarifying. 



Manganese in beech-nuts. — It has lately been ascertained, in cor- 

 roboration of experiments made some years ago, but to which little im- 

 portance was attached, that beech-nuts contain a large percentage of 

 manganese, although the soil in which they are grown may exhibit na 

 ai)preciable trace of this metal. 



Substances affecting the germination of seeds. — According 

 to a late paper by Dr. Yogel, upon the intiuence of various substances 

 on the germination of seeds, it is stated that among those most injurious 

 in this respect are dilute acetic acid, and carbolic acid, although the 

 substances in question are present in very small percentage. Solutions 

 of hydrocyanic acid, arsenic, phosphorus, &c., were found to be mucli 

 less nijurious in the same proportion than those first mentioned. This 

 explains the unsatisfactory nature of experiments for the destruction of 

 insects on plants by means of solutions of carbolic acid ; the insects, it 

 is true, being killed by a very weak solution, while at the same time the 

 plants themselves rarely survive. 



Influence of conditions of heat on the growth of plants. — 

 A paper has lately been published by Koppen, upon the relationship of 

 conditions of heat to the phenomena of growth in plants; his first 

 inquiry being limited to the questions connected with the germination 

 of the seed. The general conclusion arrived at was that variations of 

 temperature were in all cases prejudicial to the growth of the germ, even 

 when amounting to but a few degrees, and these within limits favorable 

 to energetic growth. That is to say, the germination proceeds more 

 rapidly at a low temperature of a uniform degree, than at a higher^ 

 where subjected to more or less variation. From this we derive the 

 inference that a nearly uniform spring temperature, with a cloudy sky, 

 is more favorable to rapid development of vegetation than the alterna- 

 tion of hot days and cool nights, it being of course understood that the 

 mean temperature in each case is about the same. 



Ink-plant of new granada. — Amoug vegetable substances useful 

 in the arts is one that has long been known in New Granada under the 

 name of the ink-plant, as furnishing a juice which can be used in writing 



