The authorities cited for the Commonwealth fully establish the sufficiency of the indictment. It alleges only a single offence.

The objection that it was necessary to prove the knowledge of the defendant that water had been added to the milk is groundless. Commonwealth v. Farren, 9 Allen, 489.

The practical experience of Faxon, the inspector of milk, had been such that his testimony was admissible. Carpenter v. Wait, 11 Cush. 257. Tests by means of instruments are much used in a great variety of cases, and are found to be trustworthy, and for this reason they are admissible in evidence. In each particular case, the value of the test must be estimated by the jury.

' Exceptions overruled.