quantities sufficient to maintain the operating pressure of the introduction system 30 thus control valve 44 and return line 48 or any other suitable structure such as other valves or couplings as would be apparent to one of ordinary skill in the art after reviewing the disclosure of the present invention may be used to divert scf u2014 co 2 to preparation vessel 34 such devices and structures and equivalents thereof thus comprise u201c diverting means u201d as used herein and in the claims when textile treatment material is dosed as a suspension into the treatment system 32 introduction system 30 operates with full or partial co 2 makeup via return line 48 when textile treatment material introducing is performed without co 2 makeup the control valve 44 in return line 48 remains closed throughout the introduction cycle and preparation vessel 34 is emptied of its contents during the introduction cycle for introduction of suspension with full makeup control valve 44 operates as described above in the case of partial makeup control valve 44 is operated intermittently to return scf u2014 co 2 from circulation loop 52 to preparation vessel 34 i e preparation vessel 34 is partially emptied and then refilled with return scf u2014 co 2 in the case of full or partial makeup to introduction system 30 when ncl u2014 co 2 is utilized in.