4. The spoilage of ketchup after opening depends more upon the temperature of the place in which it is kept than on any variation in the manner of processing. Fresh ketchup held, after opening, at a temperature of 95° F. kept for five days on an average without any trace of mold appearing; at 72° it kept for six days; at 67° for eight days; about 46° (refrigerator), fourteen days; and at from 30° to 60° for twenty-seven days. These figures represent the time at which the first trace of spoilage occurred in the neck of the bottle--had this been removed the figures would be much increased--and by no means represent the maximum time during which the ketchup could have been used, the maximum figures, even under these conditions of observation, varying from eight to fifty-eight days. The keeping of the ketchup in warm storage at 70° for one hundred and fifty days before opening hastened the average time of spoilage after opening about one day. The advisability of using small containers, to get the best results with a first-class ketchup, is apparent. 5. Sodium benzoate, even when used in the proportion of 0.1 per cent, is not always effective, and has an injurious effect upon the living matter of the molds, shown by the distortion and swelling of the filaments, which are filled with a coarse granular protoplasm containing much fat. 6. Artificially colored ketchup can be detected under the microscope by the fact that certain tissues, normally colorless, are dyed red, or by the presence of fine, red, amorphous particles which do not go into solution. 7. Ketchup made from whole ripe stock in a cleanly manner gives a clean appearance under the microscope, but few molds, yeasts, and bacteria being present. On the other hand, ketchup made from trimming stock, or from tomatoes that have been allowed to spoil, contains immense quantities of these growing organisms which may be killed in the process of manufacture, but still give proof of the character of the material used. Ketchup as ordinarily made from trimming stock should, therefore, be designated, so as to differentiate it from that made from sound fresh tomatoes, as the two products are radically different. This exactness in labeling is due no less to the manufacturer than to the consumer, as it is impossible to make the superior product in fair competition with the inferior one, other conditions being equal, unless the two are properly designated, there being naturally some difference in the price. Transcriber's Notes: In the text version, italics are represented by _underscores_. Missing or incorrect punctuation has been repaired. The following corrections have been made to the text:-- p.8. A majority of the manufacturers employ word, has been changed to A majority of the manufacturers employ the word. p.28. one has has, the duplicate has been removed. End of the Project Gutenberg EBook of Experiments on the Spoilage of Tomato Ketchup, by A. W. Bitting