V 



284 EXPERIMENT STATION RECORD. 



In tests of juice heaterg the coefficient of heat transmission varied from a 

 minimum of 70.9 to a maximum of 375.1, the average being 155.3. Most of the 

 low coefl5cients are said to be due to foul heating surface, as is also the varia- 

 tion in heat transmission. The heat efficiency varied from 90.13 to 96.79 per 

 cent, the average being 94.1. The juice heater tests also brought out the im- 

 portance of keeping the heaters in good condition. 



In tests of sugarhouse condensers, particularly to gain information regard- 

 ing the relative merits of the counter current and parallel curi'ent types, it was 

 found as regards temperature that there is little difference in the results when 

 worked counter current or parallel cun-ent. Pressure observations indicated 

 the desirability of liberal size and careful designing of trays, both as to the 

 size and location, in order to secure steady action and the prevention of 

 pockets. As regards quantity of injection water it was found that, other 

 conditions being the same, the weight of cooling water required i>er pound of 

 vapor is almost proportional to the difference between the temperature corre- 

 sponding to the vacuum and the leg pipe temperature, this difference varying 

 from a minimum of 6.8° to a maximum of 25.8°. As regards the amount of 

 cooling water required, there was in general a considerable advantage for the 

 counter current type of condenser over the parallel current tyi^e. 



Ventilation of cattle barns, R. Knoch {Kuhn Arch., 5 {1914), PP- 289- 

 30S). — The results of investigations on the ventilation of cattle barns led to the 

 following conclusions : 



A cow contributes only about 20,000 heat units daily to the warming of the 

 stall. The minimum permissible temperature in a cow stall may be from 17 

 to 18° C. (62.6 to 64.40° F.), and at times as low as 15° (59° F.). A complete 

 change of air in the cow stall should occur from two to three times a day, since 

 an animal should have about 50 cubic meters of fresh air hourly and the carbon 

 dioxid content should not exceed 2.4 per cent. When the air is changed from 

 1 to li times daily the limiting temi>eratiire below which the animal heat is 

 insufficient to maintain the desired stall temperature is approximately 0°. It 

 is, therefore, necessary at lower temperatures that the ventilating apparatus be 

 so regulated as to limit the air addition to below the desired amount. In such 

 cases it is advisable to provide a simple, easily regulated heater to heat the air 

 previous to its admission to the stalls. 



On excessively hot days ventilation depending on ordinary air movement is 

 insufficient and some type of ventilator is usually necessary. In cold seasons 

 the expulsion of bad air by means of foot boards and the admission and distri- 

 bution of fresh air under the roof is the safest method for uniform heat dis- 

 tribution. 



Movable hog' houses, J. M. Evvard and J. B. Davidson (Iowa Sta. Bui. 152 

 (1914), pp. 201-246, figs. 58).— It is the purpose of this bulletin to describe and 

 illustrate movable hog houses which have undergone successful tests at the 

 station. 



The essentials of an ideal hog house are pointed out as warmth, dryness, 

 abundance of light and direct sunlight, shade in summer, ventilation, sanita- 

 tion, safety and comfort as regards doorways and floors, convenience, service- 

 ability, sufficient size to shelter advantageously, durability, reasonably low first 

 cost, minimum cost of maintenance, and pleasing appearance. The important 

 considerations to be emphasized in selecting the location of the hog house are 

 said to be economy in labor and time in management, drainage, sunny exposui'e, 

 southern slope, protective windbreaks, nearness to pasture and summer shade, 

 suitable elevation, prevention of odors reaching dwelling, and lessened risk from 

 disease Infection. 



