8 July, 1907.] Use of Concrete for Silos. 401 



There would also be rather less loss in handling the raw material as the 

 milk would not be handled at all, making an additional difference perhaps 

 of I per cent., or about 2 per cent, in all. Other features may make a 

 variation, for instance, the percentage of salt added — whether a large pro- 

 portion of fresh or unsalted butter is made. The difference between salt 

 and fresh butter is from 2 to 3 per cent, in favor of the former ; then 

 if half the output be fresh, there would be a reduction on that account of, 

 say \\ per cent, on the whole output. 



Now we come to the starting point again, that is the amount of monev 

 available for distribution and how to apportion it. As butter fat, instead 

 of commercial butter, is now the basis of payment, and taking the 20 per 

 cent, overrun for simplicity as an example, if we could pav lod. for 

 commercial butter, we could pay lofl. x T.20 = is. for butter fat. 

 If we had a 16 per cent, overrun, we could pav lod. x 1.16 :=ir.6d. or 

 a fraction over iii^d. With a 13 per cent, overrun it would be lod. x 

 1.13 :r: 11.3 or a fraction over iijd. 



The foregoing is the outcome of recent investigations to ascertain the 

 actual overrun in Victorian factories treating both milk and cream. It 

 is also conifirmed by experiments in other countries, as mav be seen bv 

 reference to Farringdon and Woll's " Testing Milk and its Products," 

 pages 177 and 185. 



THE USE OF CONCRETE FOR SILOS KM) OTHER 

 FARM BUILDINGS. 



A.. S. Kcuyon, C.E., Engineer for Agricidtiire. 



Of late the American farmer has gone in largely for concrete as a 

 material for the construction of all classes of buildings. It is of greater 

 strength than any other material ; is both cooler and warmer than brick or 

 timber; is free from risk Oif fire; but what is more important, is cheaper 

 than the former and little, if any, more costly than the latter in cases 

 where the necessary raw material is easily obtainable. Timber is becom- 

 ing scarcer and dearer every year and in the sawn form has only a mode- 

 rate life, while round timber, except, perhaps, for uprights, is not 

 economical. Bricks get hotter than concrete and take longer to cool 

 do'wn. In short, concrete is. an ideal building material provided it can 

 be readily and economically manufactured. Now there is really very little 

 difficulty in maiking good concrete if some care be taken in following the 

 advice here given. 



Concrete is composed of metal (broken stone) or gravel mixed with sand 

 and Portland cement in certain proportions and wetted. In "fine" 

 concrete no metal is used, small gravel taking its place. Cement and sand 

 alone form a mortar or " compo." The proportions of the various mate- 

 rials depend upon the air voids or spaces in the metal or gravel and upon 

 the strength of concrete required, varying with the uses to which it is to be 

 put, engine foundations and hollow blocks representing the strong side, and 

 building foundations and solid walls the weaker class. The mortar or 

 "compo" of sand a.nd cement should be sufficient in bulk to fill all the 

 voids in the metal, preferably somewhat in excess, say about 10 per cent. 



