4 BULLETIN 196, U. S. DEPARTMENT OF AGEICULTUEE. 



The effect of the sudden production of a vacuum, due to condensing steam inside 

 the cans, may be seen in the strongly collapsed sides when they are played upon by 

 a stream of cold water. Number 3 cans, if a little slack-filled, or gallons will present 

 the appearance of being battered. If such cans, resting upon their sides instead of 

 on end, so that the stream is along the upper side, are struck by cold water, the col- 

 lapse at the one point may be so severe as to cause buckling or even breaking of seams. 



After the processing is completed, the pressure decreases inside the can until, 

 theoretically, it becomes zero at the temperature at which the sealing was done and 

 becomes a vacuum at temperatures below that point. As a matter of fact, however, 

 a weak vacuum is always found at the temperatxire of sealing, due to changes in the 

 product or to the action of the product upon the container in processing. Cans sealed 

 at 160° to 180° F., and stored at from 60° to 80° F. will show a very strong vacuum, 

 while those packed cold or nearly cold and stored in a warm place will show no 

 vacuum and may show actual pressure, becoming springers. 



SANITATION. 



A modern cannery is no longer the rough, crude shed that once was thought to be 

 sufficient for this purpose. First of all the location must be sanitary, away from 

 manufactxu-ing processes which of themselves are objectionable, such as soap making, 

 tanning, rendering fats, or any other processes which may give rise to noxious odora 

 or may be productive of organisms of decomposition. The yards and drives about 

 the factory should be cleaned daily, and in summer dust should be prevented by 

 frequent sprinkling or by the application of crude or specially prepared oil to the 

 drives. The application of oil is especially to be recommended where there is much 

 hauling and there is no pavement, or the factory is to be run for a short season only, 

 as in the case of tomatoes. A single application made a couple of weeks before the 

 season opens will suffice for several weeks; if the oil is put on early it will become 

 incorporated in the earth and not be tracked into the factory to any great extent. 

 The drainage must be such as to prevent any surface overflow from adjoining property, 

 and also be ample to keep the stock in good condition at all times. It should be 

 ample to care for the waste, as this is sometimes a serious problem. If the natiu-al 

 body of water available is not sufficient, settling tanks or filters may be necessary. 

 Fermenting material, such as tomato trimmings or corn refuse, should not be tolerated 

 within or near the factory. The supply of water should be sufficient for all purposes 

 and of good quality; that used in washing, blanching, and brining should be free 

 from excessive hardness or iron, otherwise the finished products may be damaged. 

 If the water for this purpose is not naturally of the right quality, artificial treatment 

 may be necessary. The water used for washing about the factory should have a good 

 pressure for cleaning. A factory with a poor location, or an insufficient or poor water 

 supply, has a handicap which is difficult to overcome. The facilities for bringing in 

 or sending out stock should be ample, so that materials used need not be delayed, 

 especially when it may mean deterioration. 



The buildings should be designed ^\dth reference to the special products to be packed, 

 but there are some features which should be common to all. The ceilings of all rooms 

 should be high, with ample provision for light and ventilation. The Hght should 

 come from numerous side windows, or, if the rooms are large, from turrets, or a saw- 

 tooth-roof construction. Either of these two arrangements can be made to give a 

 flood of light and at the same time provide good ventilation. An advantage in the 

 saw-tooth construction arises from the cooling and drying effect. "When the straight 

 section, or ^vindows, is txu-ned toward the north, the sun beating upon the southern 

 incline Avill heat the layer of air underneath, causing it to rise. This creates a circu- 

 lation within the room which tends to dry floors and tables and to lower the tempera- 

 tiu^e. Tests made in factories so constructed have shown several degrees lower tem- 

 perature on hot days than was recorded in factories having the usual form of roof. 



