29 



5 per cent, of the weigiit of the latter, the moist mixtures of the same 

 surface have a (lisi)r()i)()rtionately great i)o\ver of absorption for the tim- 

 raonia of the atmosphere in a dry season, and increasing- more than 

 pro])ortionally witli an increasing- amount of uhnin. 



Eucalyptus tkek. — Much success seems to have been experienced 

 in the introduction of several species of Eucuhiptm from Australia into 

 various parts of Europe and California; and it is probable that in this 

 plant we may have a very important addition to our material resources. 

 Its great merit consists primarily in its adaptability to regions other- 

 ■wise unsuitable for the growtli" of fore.st vegetation, in the extreme 

 rapidity of its growth, anil in the great value of the wood for economi- 

 'cal purposes. When ])lanted in marshy laud, it has a very decided effect 

 in (h-aining the soil, and freeing it from a malarious tendency ; while it 

 is said to thrive where the annual rainfall is scarcely sufticient to keep 

 ordinary trees in proper vigor. 



In one case, a specimen raised in Algiers had attained, at the end ot 

 eight years, an elevation of nearly thirty-five feet, and a circumference 

 of five feet at a distance of three feet from the ground. In Australia it 

 reaches enormous dimensions, equaling if not exceeding in height, 

 though not in circumference, the far-famed giant trees of California. 



As is well known, trees having this rapid growth are generally soft 

 and spongy, and of comparatively little value tor timber ; but the Euca- 

 lyptus is quite the reverse, tlie wood being very heavy and hard, resist- 

 ing the action of air and water, as well as of most kinds of insects. In 

 general properties it resembles the wood of the oak, and it is employed 

 very largely tor ship-timber in Australia. The growing plants dissend- 

 nate an aromatic fragrance, Avhicli is supposed to be conducive to health. 

 This is due to the volatile essential oil, which can be readily collected, 

 and is known as eiieahjptol. The leaves famish 2J per cent, of their 

 weight of this substance, which has come into use already as a solvent 

 of resins, and even of caoutchouc ; and it is warndy recoinmemled for 

 the mauufacture of varnish. It is also valuable as a febrifuge ; and 

 on this account, in Si)ain and the south of France, it has been made 

 to replace quinine with decided advantage. 



Changes in the proximate principles of herbaceous vege- 

 tables. — Deherainmaintainsthatthe proximate principles of vegetables 

 migrate from the older to the newly formed leaves, and that this nugra- 

 tion is associated with a transformation of glucose into cane-sugar, 

 while, when the seed is formed, the cane-sugar is converted into starch 

 and the albumen into gluten, both insoluble. In this way the conver- 

 sion of soluble into insoluble princii)les and the accumulation of sub- 

 stances in the seed is accounted for, and is illustrated by the following 

 experiment: If a porous vessel, containing distilled water, be pla(;ed in 

 another vessel containing a solution of cupric sulphate, the salt pene- 

 trates by diffusion into the inner vessel. If then a few drops of baryta- 

 water be added to the inner vessel, the salt is precipitated, the equili- 

 brium is disturbed, and a new portion of cupric sul[)hate diffuses into 

 the inner vessel. The salt may be again precipitated by the baryta- 

 water, and the operations repeated till eveutuall}^ the whole of the cu])ric 

 sulphate will have ])assed into the porous vessel, and there become 

 precipitated. 



Power of soils in absorbing gases. — Prof. Eeichardt, of Jena, 

 has instituted a series of experiments, with the aid of Hcrr iScheermes- 

 ser, upon the capacity of the constituents of the earth to absorb gases, 

 and has been led to the following conclusions : 1. The power of absorb- 

 ing carbonic acid gas exhibited by clay purified with hydrochloric acid, 



