ESTIMATION OF AMOUNT OF HMOGLOBIN. 157 
exposed to direct sunlight; look at them by the light 
which is reflected from this paper, and add water from 
the pipette belonging to the dropping bottle, drop by 
drop, until the colour in the two tubes is exactly the 
same. Read off the height of the column of diluted 
blood; this gives the percentage amount of hemoglobin. 
Oliver’s hzemoglobinometer differs from that of 
Gowers’ in that the degree of dilution is constant 
and the colour of the diluted blood is read off by 
comparison with a series of carefully graduated stan- 
dards. It consists of (1) a capillary glass tube with 
thick walls and ground ends, one of which is flat and 
the other pointed; this tube is mounted in a metal 
handle, the other end of which serves as a stirrer 
(fig. 27, c); (2) a small cell with an opaque white 
bottom, and provided with a cover-glass which has 
a slight bluish tint (e); (3) a series of twelve coloured 
glass discs mounted over an opaque white back- 
ground (a); (4) certain small pink glass discs used 
as riders; (5) a short glass pipette with an india- 
rubber nipple at one end and a short length of india- 
rubber tubing at the other (d); the latter fits over the 
pointed end of the capillary tube mentioned first; and 
(6) a small wax candle such as is used for Christmas 
trees. A camera tube lined with a green material is 
used to screen the eyes whilst the comparison is being 
made. 
Method of use:—Prick the patient in the usual way. 
Apply the polished end of the capillary tube to the 
drop of blood; this will completely fill the tube, being 
drawn up by capillary attraction. When quite full 
wipe both ends of the tube with the fingers and apply 
the end of the glass pipette (previously filled with 
water) to the pointed end of the capillary tube. Now 
