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APPARATT'S FOR AERATING I'LAXTS. 

 HY 



F. M. A.NDKKWS. 



I havo mado use of tlio well kiutwii P.uiiscii pumi) with sonic a(lilitif)ns 

 or inodilicatioiis for tlio puriKisc of acratiiij: water cultures. Sometimes I 

 have used it for aerating' cultuics not irrown in water also witli fjooil residts. 

 In a previous paper' I liavc sliown tlic advantai^cous eftect tliat the 

 passing of air through a water cultui-c has on the plant. A lilvc hcne- 

 ticial effect was also found when air was passed tlnougli soil in which the 

 corn plant was growing. In the paiier just icfeired to the Kekule apparatus 

 as descrihed hy Ostwald was also used for some ex])eriments with equally 

 favorable results. Of the Kukulc and P>unsen ai»paratus for the puriK).se of 

 aerating the latter, as I arranged it. will furnish by far the greater amount 

 of air to be passed through a culture. S(» far as convenience is concerned, 

 however, in other respects there is the further advantage of the Bunsen 

 apparatus in that much less space is required to operate it. The perpen- 

 dicular tube which conveys the chain of bubbles of air and water down- 

 ward must be of such a length that the sum of the lengths of the short 

 columns of water in this iK^rpendicular tube between the columns of air 

 will more than equal the depth of the solution through which the air is to 

 be passed. This necessitates a perpendicular tube of considerable length, 

 lu the Kukule apparatus I used the perpendicular tube has a length of 120 

 cm. while the culture solution had a depth of only 20 cm. Of course the 

 length of the iierpendicular tube and the speed with which the chain of 

 air and water will pass through it can be made to depend somewhat on the 

 length of the single columns of water for sometimes these columns of water 

 are short and sometimes long depending on the quantity of water which 

 enters the tube in the form of individual drops. Another drawback t() 

 the Kekul6"s apparatus is that the perpendicular tube is often rapidly 

 clogged completely with algae of various kinds, mostly those belonging 

 to the Cyanophyceae. and with iron deposits as well as some sediment. 

 In the Proceedings of the Indiana Academy of Science for 1916 Mr. C. C. 

 Beats', who carried out a piece of work on aeration under my direction, 

 has shown a brief sketch of the Kekule apparatus. At b in his diagram 

 he shows the perpendicular tube in question. In order to form bubbles 

 readily this tube as arranged should not be over 4 mm. in diameter. This 

 smallness of size of the tube, however, contributes to the accumulation and 

 stoppage of the tube. The algae as well as the iron can be quickly cleaned 

 out of the tube by using 50% or 60% HCl. Weaker strengths as 10% and 

 15% HCl were tried at first to clean the tube but they were not effective. 

 Exi^eriments are in progress to try to prevent this troublesome phase of 

 the accumulation of material in the tube. Its stoppage often occurred in a 

 few days; at other times in two weeks. This necessitated the disconnecting 



iThe Effect of Soaking ni Water and of Aeration on the (Jrowth of Zea May; 

 Bulletin of the Torrey Botanical Club, 1919, Vol. 4(5, PP. 94-100. 



'Beals, C. C. — The effect of Aeration on the Roots of Zea Mays. Proc. nd. Acat 

 of Science. 1916, P. 177. 



