Abstract: A method of estimating dimensions of an opening (36) in a body (26) comprises filling the opening (36) with a fluid that absorbs an electromagnetic radiation (40). The radiation (40) is transmitted through the body (26) and through the fluid in the opening (36). The intensity of the electromagnetic radiation, after transmission through the fluid, is determined at an area that corresponds to a radiation path through the fluid in the opening. The intensity is used to determine the absorbance of the fluid in the radiation path and consequently the length of the radiation path. In an alternative method, when the depths of the opening are already known, the intensity is used to determine concentration of a chemical in the opening.

Abstract: A reaction is performed in a micro-reactor (10), voltages being applied by a power supply (12), under the control of a processor (14), so as to cause the reagents to move and react in the channels (24?,30?,32?,34?,36?) of the micro-reactor (10). The power supply (12) also measures currents in the channels and relays this information to the processor (14). The currents are used to monitor progress of the reaction.

Abstract: A reaction is performed in a micro-reactor (10), voltages being applied by a power supply (12), under the control of a processor (14), so as to cause the reagents to move and react in the channels (24′,30′,32′,34′,36′) of the micro-reactor (10). The power supply (12) also measures currents in the channels and relays this information to the processor (14). The currents are used to monitor progress of the reaction.

Abstract: A method of estimating dimensions of an opening (36) in a body (26) comprises filling the opening (36) with a fluid that absorbs an electromagnetic radiation (40). The radiation (40) is transmitted through the body (26) and through the fluid in the opening (36). The intensity of the electromagnetic radiation, after transmission through the fluid, is determined at an area that corresponds to a radiation path through the fluid in the opening. The intensity is used to determine the absorbance of the fluid in the radiation path and consequently the length of the radiation path.

Abstract: A continuous flow microwave heated digesting system, which is especially useful for digesting samples of materials to be analyzed with an atomic absorption spectrometer (ASS), includes a chamber, a source of microwave radiation into the chamber, thin bore chemical resistant an microwave transmissive tubing within the chamber onto which the microwave radiation impinges to heat contents of the tubing, and a pump or other suitable apparatus or device for passing through the tubing the sample of material to be digested, dispersed in a digesting medium for it, which sample in the digesting medium is in the form of a discrete slug in a carrier liquid. A suitable device is provided for inserting into the carrier liquid, which is usually water, the slug of material to be digested in the digesting liquid and a backpressure controller is also provided to control backpressure on the slug and the carrier liquid n the tubing.