AGRICULTURAL BACTERIOLOGY. 



the germs of the common diseases. Its use, of course, must 

 be limited to spaces that are so enclosed as to be capable of 

 being tightly closed, and upon the farm, therefore, it can be 

 of value only in disinfecting sick rooms. It should be stated 

 that the practical use of sulphur seems to be more satisfactory 

 than its theoretical value would imply. Although we know 

 that it does not destroy all bacteria, it is nevertheless true 

 that its use by health boards in many places appears to be 

 very satisfactory, and rooms thus treated rarely give evidence 

 later of being improperly disinfected. 



The manifest desirability of some disinfectant which is in the 

 form of a vapor has led in recent years to the wide employ- 

 ment of a new disinfectant, formalin. This is a watery solu- 

 tion of formaldehyde gas. The gas acts as a violent poison 

 upon bacteria. Solutions of I to 10,000 are sufficient to 

 destroy the vitality of resisting bacteria immersed in the solu- 

 tion. The material looks like water, and may be used for 

 washing, thus disinfecting any clothing which can be im- 

 mersed in water. As a material for washing clothing it is 

 extremely efficient, and is as harmless in its action on deli- 

 cate fabrics as pure water. As a general wash for rooms or 

 stables it is hardly practical, since the gas given off from it is 

 very disagreeable and oppressive to the eyes. But the use of 

 formalin gas has recently been very widely recommended. 

 Special forms of apparatus are made which produce this gas 

 in large amount, and the gas made in the machine may be 

 conducted by rubber tubing into a room to be disinfected. A 

 simpler method of disinfection can hardly be conceived than to 

 close a room tightly, and to run this tube, connected with the 

 machine, through the keyhole, and then start the manufacture 

 of the formaldehyde gas. These machines have been brought 

 to a very high state of efficiency and have been rapidly adopted 

 by health boards in recent years. But just as in the case of the 

 use of sulphur fumes the efficiency of the vapor as a means of 



