48 



THE ALUMNI JOURNAL, 



saplings on waste lands. I planted a lot 

 in my garden in 1869, and when I left in 

 1890 there were trees 30 to 40 feet high 

 and upward. From this experiment I 

 conclude that trees 50 years old would be 

 large enough for all ordinary purposes to 

 which the timber is applied." — Amer. 

 Drug. a7id Pharm. Record. 



THE PRACTICAL USE OF OZONE. 



When electric sparks are passed 

 through the air a peculiar odor is soon 

 noticed. This odor arises from the pres- 

 ence of ozone, which is produced from 

 the oxygen of the air when the latter is 

 subjected to the action of electricity. 



Ozone is one of the most powerful oxi- 

 dizing agents known, and, although no 

 method for producing has been discovered 

 which is as practical as we would like to 

 have it, ozone has still achieved some 

 practical successes. It has been used in 

 the artificial ageing of brandy, sweet and 

 heavy wines and liquors. It improves 

 the aroma of coffee and renders uninjuri- 

 ous the disagreeable odors of the coffee 

 beans. It improves tobacco. One of the 

 most interesting and recent uses of ozone 

 {Brooklyn Manufacttirer^ is to improve 

 the resonance of wood, and to artificially 

 age wood. 



The wood is placed from 12 to 24 

 hours in a closed and warmed room into 

 which ozonized air is conducted. In this 

 way the wood hardened and becomes 

 resistant to exposure, and also more 

 resonant. The operation of thickening 

 linseed oil in the manufacture of lino- 

 leum, which is a process usually requir- 

 ing several months, can be finished in a 

 few days by the use of ozone. In bleach- 

 ing linen ozone is very eSective and re- 

 quires only one-third as much time as the 

 grass bleach; which is, of course de- 

 pendent on the weather and the time of 

 year. One of the recent technical uses 

 of ozone is in the production of pure de- 

 rivatives of starch, as, for instance, sol- 

 uble starch, dextrine and "crystal gum," 

 the ozone assisting in the removal of all 

 substances which give a dark color, an 

 odor and disagreeable taste. In cheap 

 production ozone offers an attractive 

 problem to electricians. — Amer, Drug, 

 and Pharm. Record. 



LIQUID AIR. 



At a recent meeting of the Chemical 

 Society, Professor Dewar exhibited a 

 portable apparatus for making liquid air 

 or oxygen, and showed that by attach- 

 ing a silver flask, containingabout a liter 

 of liquid air, to a pump, within twenty 

 minutes they could reduce it to a solid. 



He then referred to experiments made 

 in order to determine the corrected dens- 

 ity of oxygen. Following the classical 

 researches of Joule and Playfair on the 

 coefficient of expansion, he had made use 

 of liquid air for taking the specific grav- 

 ity of a number of bodies. A silver ball 

 was immersed in a flask of liquid air. On 

 withdrawing it immediately it was ob- 

 served to be quite dry, owing to the 

 liquid around it assuming the spheroidal 

 state. On replacing it in the liquid, after 

 some minutes a distinct hissing sound 

 was heard which indicated the point 

 where the ball had reached the same 

 temperature as the liquid. In this man- 

 ner the figures for bismuth (1.3), plati- 

 num (1.386) and a number ot others had 

 been obtained. These lead to the calcu- 

 lation that oxygen had a constant dens- 

 ity of 1.367. 



An interesting lecture experiment was 

 next shown. A sealed flask containing 

 the vapor of bromine was exhibited, and 

 the top was rubbed slightly with a cotton 

 wool mop dipped in liquid air. Gradu- 

 ally the red color faded away as the tem- 

 perature in the flask was reduced by the 

 evaporation of the liquid air. This was 

 explained as due to the liquefaction and 

 subsequent solidification of bromine, 

 which, in the solid state, forms beautiful 

 red crystals. Solidified nitric oxide looks 

 like copper sulphate. 



Finally Professor Dewar pointed out 

 some of the difficulties in the way of ob- 

 taining liquid hydrogen. Air was cheap 

 enough, but the case was different with 

 pure hydrogen. Then again, a very large 

 amount was needed, owing to its excessive 

 lightness, and, said the professor, " The 

 expense is awful." It was quite evident 

 that he still hoped to get over these diffi- 

 culties. — Amer. Drug and Pharm. Record. 



