Patent ID: 7028488

Claim:
A method of dispensing a liquid first material comprising a first composition of multiple components that normally fractionate upon boiling, said method comprising: (a) providing a source container containing said liquid first material to be dispensed, said source container containing a vapor phase in contact with said liquid first material; (b) providing a receiving container; (c) transferring a portion of the liquid material in said source container to said receiving container and leaving a remainder of liquid material in said source container; (d) providing a second material to be added to said source container, said second material having a second composition of components chosen from said multiple components and which second composition is different from that of said first composition and comprises at least one of said multiple components, said second composition and the mass of said second material to be added to said source container for a given mass of liquid material transferred in step (c) being predetermined to maintain the composition of said remainder of liquid material in said source container substantially the same as said first composition, and wherein the predetermined mass of said second material to be added is less than said given mass of liquid material transferred, and said predetermining step comprising calculating said mass of said second material to be added for said given mass of liquid material transferred, said calculating step accounting for the differences between the compositions of the liquid and the vapor phases of said first material; and (e) transferring to said source container said predetermined amount of said second material.