ESTIMATION OF TOTAL SOLIDS. 219 



The dishes should be arranged in a shallow tray — a photo- 

 graphic dish is suitable — according to their numbers from left 

 to right, six or seven in a row, beginning at the bottom — i.e., 

 the side nearest the operator. This arrangement is chosen so 

 that any milk accidentally dropped from the pipette will not 

 fall into a dish which has been previously filled, but into an 

 empty dish which can be easily wiped. The tray containing the 

 dishes should be on the left of the tray in which the samples are 

 placed. The samples should be arranged in order in rows, 

 beginning at the left-hand bottom corner and going upwards — 

 i.e., away from the operator — and should, if in cans, have their 

 lids turned back over the next sample can. The taking of 

 samples for the estimation of total solids is much facilitated by 

 having an assistant to stir the milk. The measurement of the 

 quantities of milk for analysis is done as follows : — The assistant 

 stirs No. 1 can, and when the cream has been mixed the chemist 

 plunges the pipette into the milk and sucks it up till it enters 

 the mouth ; it is advisable to throw away this first quantity. 

 The milk is again sucked up, the finger placed over the end 

 of the pipette, and the milk allowed to run down to the mark, 

 care being taken that air bubbles are not included in the portion 

 measured. The pipette is held over dish No. 1 and the finijier 

 removed ; the milk runs into the dish, and the drop adhering; 

 to the end is removed by touching it against the side of the 

 dish ; the last drops must not be removed by blowing, ilcan- 

 while the assistant has closed can No. 1 and stirred can No. 2, 

 from which 5 grammes are measured in a similar manner, without, 

 however, washing out the pipette ; this is transferred to dish 

 No. 2, and the whole of the samples are taken similarly. 



The next step is to enter the designation of the samples and 

 the number of the dish into which each has been placed in a 

 book provided for that purpose ; the tray containing the dishes 

 is then conveyed to the water-bath. The water-bath should be 

 of eopper, about 6 inches deep, and provided with a lid containing 

 a suitable number of holes in which the dishes can rest : the 

 number of these will vary with the number of samples to be 

 daily examined ; it is convenient to have a projecting collar 

 about a quarter of an inch deep round each hole, as this facili- 

 tates the putting on and removal of the dishes, and each should 

 be provided with a lid. If steam is laid on, the bath should be 

 heated by means of a coil laid in the bottom, through which the 

 steam circulates ; the exit of this coil should be connected with 

 a condenser, and the condensed steam serves to supply the 

 laboratory with distilled water. If steam be not laid on, the 

 bath must be supported on an iron support at such height as to 

 allow of a burner being placed underneath ; in either case an 



