DISINFECTION. 323 



No. 37. Decay of Fruit. Select some sound apples and inoculate them 

 with mold spores by dipping the tip of a knife-blade into a mass of mold 

 spores of the growths in No. 34 and thrusting the tip through the skin of 

 the apple. It will be best to inoculate different apples with each of the 

 kinds of mold that have grown on the objects in No. 34, some of which 

 will probably be the species to produce decay. Place the apples in a fruit 

 jar, close the mouth, not too tightly, and set aside in a warm place. Ex- 

 amine day by day and note that decay soon begins, starting at the inocu- 

 lated points. Allow the decay to continue till the mold breaks through 

 the surface and produces spores. If decay does not occur, it means that 

 the species of mold used were not those that produce decay, and the 

 experiment should be repeated with molds from other sources. 



DISINFECTION. 



No. 38. Disinfectants. Of the many disinfectants in use three are of 

 particular practical value. These, in the strength commonly used, are the 

 following : 



Carbolic Acid Solution, 120. 



Carbolic acid crystals, 2 5 grams 



Water, 500 c.c. 



In weighing the crystals of carbolic care should be taken not to touch 

 them with the fingers since they will burn the skin. 



Corrosive Sublimate Solution, i-iooo. 



Corrosive sublimate, i gram 



Water, 1000 c.c. 



In making and handling these solutions it should be borne in mind that 

 they are very poisonous. 



Chlorid of Lime. 



Fresh chlorid of lime, 2 5 grams 



Water, 500 c.c. 



This disinfectant is cheap and effective if fresh, but it will not keep, 

 and should be made up at the time of using. One pound of the chlorid 

 of lime in six gallons of water will make up an efficient, cheap disinfectant 

 for disinfecting walls and floors of rooms and has the advantage of being 

 non-poisonous. 



No. 39. Testing Disinfectants. Mix the white of an egg with ten times 

 its bulk of water, and place the material in a series of test-tubes filling each 

 about one-third full. To the different tubes add the following: a. no 

 addition; b. 1/4 gram salt; c. i gram salt; d. 2 grams sugar; e. 5 grams 

 sugar;/, one drop of corrosive sublimate solution (i-iooo); g. six drops 

 of corrosive sublimate solution; h. one drop of formalin; i. three drops 



