42 Transactions. 



11. The general form of the conic which is satisfied by the co- 

 ordinates of a point and of its isogonal conjugate is 



a (/a + mfi + ny) + (//3y + tllya + tlaft) = 0, 



the centrum of the conic being the intersection with la + ^"jS + ?iy = o 

 of either the internal or the external bisector of the angle A of the 

 triangle of reference. 



The locus of a point moving so that the line joining it to its isogonal 

 conjugate is parallel to the line la + w/3 + jiy = o is the cubic 



{mc - nb) a {ft' - y') + {na - Ic) /3 (y-" - a-) + [Ih - ma) y (a- - /3-) = 0, 



which, if any two of the three quantities mc — nh, va — ic, lb — via be 

 equal or have their sum zero, reduces to a conic and either the internal 

 or external bisector of an angle of the triangle of reference. If the two 

 latter quantities be equal, the conic is 



{na — Ic) {a? + fty) — {mc — nb) a{(3 -\- y) = o, 



which, since a (w + ?t) = / (6 + c), at once reduces to the form I of 

 section 1 of this paper. A similar reduction occurs if the sum of the 

 two quantities in question be zero. 



Art. IX. — The Technical Analysis of Sliped Wool. 

 By A. M. Wright, F.C.S. 



[Bead before the Philosophical Institute of Canterbury. itJi November, 1908.] 



New Zealand exported in 1906 wool to the total value of £6.765,655. 

 weighing 154,384,5681b. Of this, 15,049,470 lb., valued at £752,639, was 

 sliped wool. 



Sliped w^ool is the wool obtained from skins which have been washed 

 in water to remove the adhering sand and dirt, together with a certain 

 amount of the fat. After partially drying the skins in centrifugals the wool 

 is removed by depilation and dried. 



This is the process of treating the skins of sheep and lambs killed at the 

 freezing-works in the Dominion. The sliped wool exported from New- 

 Zealand is almost exclusively a freezing-works product. 



Two }-ears ago a Royal Commission was appointed by the New Zealand 

 Government to inquire into the cause of fires on wool-ships. Whilst some 

 of the evidence taken before this Commission showed that fires had 

 occurred in sliped w^ool, it could not be shown that this wool, either through 

 excessive moisture or fat, had been the cause of fire. 



In order to guard as far as possible against fires originating in sliped 

 wool, either through excessive moisture or on account of foreign fatty 

 matter, and, further, to obtain a standard quality for their output of wool, 

 one of the largest meat-freezing and wool-export companies now requires 

 that samples of wools from their various factories be regularly examined 

 in their chemical laboratory — determinations of moisture, natural wool- 

 grease, other fatty matter, sand, dirt, and lime, and wool-fibie being made. 



