Horwill, J.

1. The petitioner has been convicted by the Second Presidency Magistrate of selling adulterated butter and thereby committing an offence punishable under Section 5, Clause (1)(a) and (b) of the Madras Prevention of Adulteration Act, read with Rules 28 and 29 under the same Act. He has been sentenced to pay a fine of Rs. 100.

2. The prosecution case rests entirely on the evidence of the Corporation Analyst, with the figures that he gave for certain tests carried out by him and more important still, the inferences which he drew from the figures obtained. The accused examined on his side a gentleman who has had some experience of analytical work under the Bombay Government; and fortunately the figures that he obtained upon analysis were very much the same as those given by the Government Analyst in so far as the tests conducted by these two gentlemen were the same. The Government Analyst conducted four tests. He estimated the Beichert Wollny value, the Befractive Index, and the Saponification value; and he then calculated from the Beichert Wollny number and the Saponification value the Juckenack and Pasternack value. D.W. 1 estimated the Reichert Wollny value and the