When upon examination before any court it appears that any child within the age previously mentioned in this Act was engaged or used for or in any business, exhibition, vocation, or purpose prohibited in this Act; and when upon the conviction of any person of a criminal assault upon a child in his custody, the court before whom such conviction is had, shall deem it desirable for the welfare of such child, that the person so convicted should be deprived of its custody; thereafter such child shall be deemed to be in the custody of court, and such court may in its discretion, make such order as to the custody thereof as now is, or hereafter may be, provided by law in cases of vagrant, truant, disorderly, pauper, or destitute children.