A method to manufacture bags containing bicarbonate powder,each bag having two pockets communicating by means of a lowerU-shaped channel, the bottoms of the pockets and the outerside of the lower channel defining the bottom of the bag. Themethod comprises the steps of longitudinally folding a plasticfilm, welding the folded film so as to form a semifinishedproduct comprising a succession of open bags, with therelative pockets arranged transverse to the folding line,cutting the semifinished product so as to separate the openbags, and filling the pockets of each open bag withbicarbonate powder. Forming the semifinished product comprisesthe steps of performing, along the folding line, a successionof first welds shaped as the bottom of the bags and performinga succession of second welds, which are transverse to thefolding line, so as to divide the pockets of each pair ofpockets from one another and to define the inner side of thelower channel.
