540
JOURNAL OF CHEMICAL EDUCATION
MARCH, 1931
leg of the U-tube. This procedure creates a slight suction on the bulb when the lower cock is opened. Introduce some of the gmoline into thefilling cup a t top, the air being displaced by shaking and tilting the apparatus. Open the l m e r two-way cock so that the bulb is in connection with the short leg of the U-tube. Open the upper cock and allow small portions of the gasoline to enter the bulb so as to saturate the air in the bulb with gasoline vapor. NEVER allow the filling cup to become entirely empty of gasoline because excess air would then enter the bulb. Continue to pour gasoline into the filling cup and to allow small portions to enter the bulb until the air is saturated. When this point is reached, further addition of gasoline will not change the difference in level of the two legs of the U-tube. During this procedure, it is desirable occasionally to remove gasoline from the long leg of the U-tube so as to maintain a slight suction of the bulb a t all times. When the air in the afiaratus has become saturated, adjust the levels in the two legs of the U-tube by adding or removing gasoline with the pipet until the levels are equal. Read and record the cc. increase i n erolume indicated on the graduated short leg. Read and record pressure i n mm. Bulb capacity of this apparatus is ..... Substitute in formula below: Vapor pressure (in mm" =
Increase in volume (in cc.) X Barometric pressure (in mm.) Bulb capacity (in cc.) Increase in volume (in cc.)
+
Too Much Lime Ties Up Soil Iron. A short time ago, Dr. William Crocker of the Boyce Thompson Institute for Plant Research found a rose-grower of the Middle West who was losing about half of his roses from yellowing of the leaves and stunted growth. The soil had been very carefully limed and tested to make sure that it was neutral or alkaline. I t was suggested that the soil was too alkaline, with the side result that the iron was rendered unavailable. The roses, like humans under similar conditions, were anemic, lacking their iron ration. The greenhouse grower did not take very kindly to the suggestion, having gone to great lengths to produce technically perfect, tested alkalinity of the soil. On his return to the Institute, Dr. Crocker suggested to Dr. F. W. Zimmerman that be try out this point, with the result that in one of the Institute green houses today a jury of roses is deciding the question themselves. Bushes of one variety grown in rather strongly acid soil are flourishing, while those on slightly alkaline soil are practically on their death-bed. While all roses will not react in the same degree to this condition, still the principle probably holds in general.-Science Seraice
