700 Report of the Consulting Engineers on. the Trials of 
result that complete analyses were made and the results were 
furnished even while the engines were running. It will thus 
be easy, in future trials, to arrange for collecting samples of the 
products of combustion continuously during a whole run, and 
to determine also the effects of different modes of firing, and the 
management of the ash-pan and chimney-dampers. Mr. J. 
Pattinson is the Public Analyst of Newcastle, and Mr. J. E. 
Stead occupies the same position at Middlesbrough. To the 
latter gentleman is due the invention of an apparatus, by means 
of which the analysis of the products of combustion is rendered 
easy and expeditious. The process consists of two parts — first, 
the collection of the products, and secondly their analysis. 
Tlie apparatus for collecting the gases consists (see Fig. 1) of a mercury 
vessel A, 7 in. high and If in. diameter, which is connected by the tube H 
Fig. 1. 
and cock D to the place from whence the sample is to be drawn ; in the case of 
the engines at Newcastle, from a spot just above the tubes and below the 
blast nozzle. B is a receiver into which the mercury can flow from the vessel 
A through the pointed pipe and cock E. G is an india-rubber pipe connect- 
ing the bottoms of the two vessels, and capable of control by the cock F. The 
vessel A being full of mercury, and vessel B emptj', the cocks E and^ closed, 
the pipe H is connected to the desired point of the smoke-box, the cocks D and 
C are opened, and sufficient of the products are sucked through the tube I to 
ensure all the air being withdrawn. The cock C is then closed, the cock E 
opened, and the mercury is allowed to flow out at any desired speed. The 
products of combustion are thus drawn into the vessel A through the pipe H, 
and, depending on the rate at which the mercury is permitted to flow, the 
sample in A may be collected either in a few minutes or the collection may 
extend over as many hours .as may be desired, and it is evident that an 
average sample will be obtained. To refill A with mercury, the cocks F 
and C must be opened and the vessel B must be raised to a higher level 
than A, when the mercury will flow back by the tube G, and all will be 
