Drinking- Water and some of its Impurities, 119 



thing which could be pronounced injurious, and yet there 

 is no destruction of the poisonous material ; it is still in the 

 liquid, although not to be recognized, and such water is 

 now regarded by physicians as the most direct and certain 

 vehicle for the transmission of Asiatic cholera." (Fifth 

 Annual Eeport of the State Board of Health of Mass., 

 Jan., 1874.) It is now very generally held that drinking- 

 water polluted by even a very small amount of excremental 

 matter from those suffering from typhoid fever, is capable 

 of propagating that disease. This was shown most re- 

 markably by the case of the village of Lausen, Switzerland, 

 when all the inhabitants except those living in six houses 

 procured their water from one spring. Typhoid fever made 

 its appearance in nearly every house except the six that 

 did not use the water from the spring: seventeen per cent 

 of the whole population had the disease, ihe cause was 

 found a mile away at an isolated farm-house on the opposite 

 side of a ridge of land, where an imported case of typhoid 

 fever, followed by two others, had occurred shortly before 

 the outbreak. From the valley where this farm-house was 

 situated, there extended to the valley of Lausen, a stratum 

 of porous earth, based on some impervious floor dipping 

 towards Lausen, and a small brook that ran near the house 

 into which the dejections of the typhoid patients were 

 thrown, and in which their linen was washed being used 

 to irrigate some meadows, sank into the porous stratum, 

 passed through it, under the ridge, and poisoned the Lausen 

 spring. To prove this, careful experiments were made. 

 Eighteen cwt. of salt were dissolved at the meadows, which 

 was followed by its appearance in the spring. Fifty cwt. of 

 flour then being mixed with the water, no traces of it could 

 be discovered at the spring — the water evidently filtering 

 through the earth, and not passing by an underground 

 channel. This filtering removed the suspended flour but 

 could not remove ihe dissolved salt. In this case at Lausen, 



