(9) Cooking connections: It is preferable to drill the inlet nozzle at bottom of tank at the lowest point possible and to admit steam on two sides of nozzle not opposite but on an angle as shown in plan. This prevents “dancing” tanks. _Check Valves._--Check valves are placed in the admission valve to prevent floaters or foreign materials entering lines and stopping the control valves and steam and water. _Inlet Header._--For usual purposes steam and water are admitted into the tank at one point and steam at one, see _Nos. 12-a_ and _12-b_ on diagram. If tank water is being collected and evaporated, line _12-c_ is introduced and used as follows: Ordinarily the use of _12-b_ is for admitting water into bottom of tank in case the oil line after tank contents are cooked and settled are below the draw cocks. In the event tank water is being saved to avoid weakening tank water by introduction of cold clean water, this result is accomplished by pumping tank water into the tank via the connection _12-c_. If tank water is not being evaporated, _12-c_ line and connection is omitted. _Draw Down Pipe._--If the oil is high and water appears at the draw-cocks _14_ and _15_, then the content is lowered by opening cock _No. 13_ and lowering the body as much as required. _Oil Draw Cocks, 14 and 15._--When the tank is cooked, oil settled and the tank raised or lowered by use of _No. 12_ connections or _No. 13_ cock, the oil belt should be such that the bottom of it is about on a line with cock _14_, and the main body of oil is drawn through cock _No. 15_. =Surface Box Treatment.=--After the oil is drawn out of the tank, the residue is dumped into the surface box. Anything that has not been thoroughly cooked will float on top in the vat. These floaters should all be skimmed off and put back into the tank to be re-cooked. The contents should be thoroughly agitated with a pole or rake, cooked fifteen minutes, allowed to settle and the oil carefully skimmed off. This should be done two or three times on each vat so as to free all the oil possible. If tank water is being collected the boiling is done by steam jacket on the box; if not, by direct application of free live steam. In either case stir contents freely.