The Inert gas blanket

The use of a large funnel attached to a stream of inert gas situated above the bench is particularly useful when opening bottles of hygroscopic or hydrolytically unstable materials. This technique relies for its success on a fast stream of clean and dry inert gas. It is of course wasteful when used over long periods, but it does allow almost the same flexibility of manipulation as on the open bench. 

The move from the open bench to a closed system involves loss of flexibility, and so a greater degree of pre-experimental planning is necessary. With careful operation, the moisture content of the atmosphere in a dry-box can be reduced to such a low level that one can do experiments in which 10 mol of water in reagents is tolerable. To achieve this level it is important that the techniques be used intelligently, and it is worth examining 

Both the dry-box and the dry-bag offer a considerable degree of experimental flexibility and are very suitable for larger scale preparative work in which catalytic amounts of impurities are unimportant. However, in this context it is very important to remember that some materials, and expecially natural products such as cork, wood and paper, have a high water content, however carefully they may have been dried and/or degassed, and that they should therefore never be used inside a dry-bag or dry-box. 

A dry-bag is a bag, usually about 0.5 x 1 m, made of a transparent, inert and tough film or sheet which has an easily sealable entry port for inserting apparatus and several ports for admitting purging gas, electrical leads, etc., and at least two gloves so that operations can be done inside it. 

The dry-box, also known as glove-box, consists essentially of a metal box with a viewing window and (at least) two rubber or plastic gloves, a port, usually with a lock for the introduction of reagents or pieces of equipment, and ports for the in-flow and out-flow of inert gas, for electrical leads, etc. The atmosphere inside the box is established by a stream of well-dried and deoxygenated inert gas which is usually kept slightly above atmospheric 

---