161 
In all cases only half an ounce of baryta solution was 
used. 
Minimetric House and Workshop Method. 
A. 
This method is partly described in the report on the air 
of mines, and long tables given. There were shown two 
modes of using it, first, with baryta water; second, with 
lime water. 
Suppose we desire to know if the air contains more 
than 0*04 per cent of carbonic acid, we fill a bottle con- 
taining 5 *422 ounces with air by pumping as elsewhere 
described, with a little finger pump, and shake in it 
half an ounce of baryta water. If there is any precipitate 
at all, the amount of carbonic acid in the air is above 0*04 
per cent. This would indicate that the air is less pure than 
outside. 
If we allow 0*06 p.c. of carbonic acid in a room, we take 
a bottle of the size of 3*6+^ ounce=4*l ounces, or 116*23 
c.c., and if, after a trial as before, we find a precipitate, 
however small, or a decided, although slight milkiness, the 
air is deteriorated beyond 0*06. This relates to dwelling- 
houses. If for workshops £ p.c. (0*25) is allowed, a 
bottle of 0*867+0*5 ounce=T367 ounces or 38*744 c.c. is 
sufficient. This could go into the waistcoat pocket. 
If 0*5 or i per cent, is permitted, a bottle of 0*433+0*5 
ounce is enough=0*933 ounces or 26*475 c.c. This amounts 
to nothing more than shaking an ounce bottle. The addition 
of half an ounce is for the baryta water. 
