122 OF THE INORGANIC CONSTITUENTS OF PLANTS. 



the eggs conveyed to this place by birds do not 

 find the conditions necessary for their development, 

 which they found in the former place.* 



How much more wonderful and inexplicable does 

 it appear, that bodies which remain fixed in the 

 strong heat of a fire, have under certain conditions 

 the property of volatilizing,and, at ordinary tempera- 

 tures, of passing into a state, of which we cannot 

 say whether they have really assumed the form of a 

 gas or are dissolved in one ; Steam or vapors in 

 general have a very singular influence in causing 

 the volatilization of such bodies, that is, of causing 

 them to assume the gaseous form. A liquid during 

 evaporation communicates the power of assuming 

 the same state in a greater or less degree to all sub- 

 stances dissolved in it, although they do not of 

 themselves possess that property. 



Boracic acidf is a substance which is completely 

 fixed in the fire ; it sufl*ers no change of weight ap- 

 preciable by the most delicate balance, when ex- 

 posed to a white heat, and, therefore, it is not 

 volatile. Yet its solution in water cannot be evap- 

 orated by the gentlest heat, without the escape of a 

 sensible quantity of the acid with the steam. Hence 

 it is that a loss is always experienced in the analysis 

 of minerals containing this acid, when liquids in 



* The itch-insect (Acarus Scahiei) is considered by Burdach as the 

 production of a morbid condition, so likewise lice in children ; the 

 original generation of the fresh-water muscle (mytilus) in fish-ponds, 

 of sea- plants in the vicinity of salt-works, of nettles and grasses, of 

 fish in pools of rain, of trout in mountain streams, &c., is according to 

 the same natural philosopher not impossible. A soil consisting of 

 crumbled rocks, decayed vegetables, rain and salt water, &c., is here 

 supposed to possess the power of generating shell-fish, trout, and salt- 

 wort (salicornia). All inquiry is arrested by such opinions, when 

 propagated by a teacher who enjoys a merited reputation, obtained by 

 knowledge and hard labor. These subjects, however, have hitherto 

 met with the most superficial observation, although they well merit 

 strict investigation. The dark, the secret, the mysterious, the enigmatic, 

 is, in fact, too seducing for the youthful and philosophic mind, which 

 would penetrate the deepest depths of nature, without the assistance 

 of the shaft or ladder of the miner. This is poetry, but not sober 

 philosophical inquiry. 



I The acid from borax. 



