A container assembly is disclosed which incorporates a chemical indicator normally hermetically sealed from the ambient atmosphere, but exposed to the atmosphere upon opening of the container assembly. The indicator is adapted for changing appearance, either color or granule or crystal form, upon exposure to moisture or oxygen. The indicator is either located in the interior of a hermetically sealed container, or is sealed in a frangible envelope which is operatively associated with a closure member of the container and is ruptured upon opening, or attempted opening of the container.

Tamper-evident closure apparatus for internally pressurized containers includes a closure provided with a mechanism for venting the internal pressurized gas upon initial unsealing of the container and a tamper-indicating device adapted to be acted upon by the vented gas to indicate that an initial unsealing of the container has occurred. The tamper-indicating device may be, for example, chemically activated to change colors when acted upon by the vented gas or may be mechanically activated so that venting of the pressurized gas causes a visibly apparent disruption, distortion or the like to indicate initial unsealing of the container.

In order to simplify the operation for determination of the acid-base status of blood, composed of the values for pH, pCO.sub.2 and the base excess BE, the base excess BE is determined through measurement of the pH-value at a pCO.sub.2 of about 0 mm Hg. The pH-values may be determined photometrically, in which case the indicator solution for measuring the actual blood-pH is an aqueous solution of 40 micromol/l bromthymol blue plus 0.2 g/l sodium dodecylsulfate plus 1% ethanol; and for measurement of the base excess BE is an aqueous solution of 65 micro mol/l naphtholphthalein plus 0.2 g/l sodium dodecylsulfate plus 15% dimethylsulfoxide, which are measured at a wavelength of 635 nm. If desired, one may use a single solution for measuring both actual blood-pH as well as the base excess BE, composed of 16 micromol/l bromthymol blue plus 34 micromol/l naphtholphthalein plus 0.15 g/l sodium dodecylsulfate, which is measured at 615 nm wavelength.

A tamper-indicating device which is attached by adhesives to a closure and which includes a sheet of material, sensitive to an ambient condition such as light or oxygen, that effects a time-delayed, irreversible change in appearance in response to exposure to the condition, which is automatically exposed upon the opening of a closure, such as the removal of a bottle cap from a bottle. The device consists of a lower sheet impermeable to the ambient condition and shaped to be attached at an underside to a lower closure member, an intermediate sheet superposed to the lower sheet and including the sensitive material, and an upper sheet, impermeable to the ambient condition, and superposed to the intermediate sheet and shaped to be attached to an upper closure member. A first, relatively strong adhesive which is used to attach the lower sheet to the lower closure member and to the intermediate sheet, and to attach the upper sheet to the upper closure member. A second, relatively weak adhesive is used to join the upper surface of the intermediate sheet to the underside of the upper sheet at the peripheries of the sheets, so that upon opening the closure, the upper sheet is separated from the intermediate sheet, thereby exposing the sensitive material to ambient light. The adhesives are selected to be impermeable to the ambient conditions as well. The tamper-indicating device may be used with cellophane packages and inserted between upper and lower sheets and positioned to form an integral part of the heat sealed edges of such packages.

A method of detecting the defective portion of sealing comprising injecting into a moisture-tight container or package having a sealed portion a detection liquor consisting essentially of a colored liquid organic compound small in surface tension and high in permeability into small clearances. The defective portion of sealing is readily detected by exudation of the detection liquor outside the moisture-tight container.