Determination of methaemalbumin in plasma.

to a Leeds and Northrup Cleretrend 12 point recorder, provision being made for matching the photocell outputs. The recorder selects each channel in turn and prints a dot corresponding to the deflection from that channel. At the paper speed of 3 in. per hour the resultant trace is a continuous line. Channel identification is by colour and number. This type of recorder was chosen after careful consideration of those available and has proved satisfactory. Future systems would be improved by the addition of a multipoint selector, now available for this particular recorder, which allows those channels not in use to be kept clear of the chart. In the present machine, a built-in test circuit, when switched on, applies different millivolt potentials to each channel not in use, allowing those channels to trace out steady lines and thus avoid confusion with channels carrying clot lysis information. A photograph of the complete assembly is shown in Figure 3.